merge(3p/git): Merge git subtree at v2.29.2 r/1890

This also bumps the stable nixpkgs to 20.09 as of 2020-11-21, because
there is some breakage in the git build related to the netrc
credentials helper which someone has taken care of in nixpkgs.

The stable channel is not used for anything other than git, so this
should be fine.

Change-Id: I3575a19dab09e1e9556cf8231d717de9890484fb

1 files changed, 373 insertions, 0 deletions

diff --git a/third_party/git/t/t4215-log-skewed-merges.sh b/third_party/git/t/t4215-log-skewed-merges.sh
new file mode 100755
index 0000000000..28d0779a8c
--- /dev/null
+++ b/third_party/git/t/t4215-log-skewed-merges.sh
@@ -0,0 +1,373 @@
+#!/bin/sh
+
+test_description='git log --graph of skewed merges'
+
+. ./test-lib.sh
+. "$TEST_DIRECTORY"/lib-log-graph.sh
+
+check_graph () {
+	cat >expect &&
+	lib_test_cmp_graph --format=%s "$@"
+}
+
+test_expect_success 'log --graph with merge fusing with its left and right neighbors' '
+	git checkout --orphan _p &&
+	test_commit A &&
+	test_commit B &&
+	git checkout -b _q @^ && test_commit C &&
+	git checkout -b _r @^ && test_commit D &&
+	git checkout _p && git merge --no-ff _q _r -m E &&
+	git checkout _r && test_commit F &&
+	git checkout _p && git merge --no-ff _r -m G &&
+	git checkout @^^ && git merge --no-ff _p -m H &&
+
+	check_graph <<-\EOF
+	*   H
+	|\
+	| *   G
+	| |\
+	| | * F
+	| * | E
+	|/|\|
+	| | * D
+	| * | C
+	| |/
+	* / B
+	|/
+	* A
+	EOF
+'
+
+test_expect_success 'log --graph with left-skewed merge' '
+	git checkout --orphan 0_p && test_commit 0_A &&
+	git checkout -b 0_q 0_p && test_commit 0_B &&
+	git checkout -b 0_r 0_p &&
+	test_commit 0_C &&
+	test_commit 0_D &&
+	git checkout -b 0_s 0_p && test_commit 0_E &&
+	git checkout -b 0_t 0_p && git merge --no-ff 0_r^ 0_s -m 0_F &&
+	git checkout 0_p && git merge --no-ff 0_s -m 0_G &&
+	git checkout @^ && git merge --no-ff 0_q 0_r 0_t 0_p -m 0_H &&
+
+	check_graph <<-\EOF
+	*-----.   0_H
+	|\ \ \ \
+	| | | | * 0_G
+	| |_|_|/|
+	|/| | | |
+	| | | * | 0_F
+	| |_|/|\|
+	|/| | | |
+	| | | | * 0_E
+	| |_|_|/
+	|/| | |
+	| | * | 0_D
+	| | |/
+	| | * 0_C
+	| |/
+	|/|
+	| * 0_B
+	|/
+	* 0_A
+	EOF
+'
+
+test_expect_success 'log --graph with nested left-skewed merge' '
+	git checkout --orphan 1_p &&
+	test_commit 1_A &&
+	test_commit 1_B &&
+	test_commit 1_C &&
+	git checkout -b 1_q @^ && test_commit 1_D &&
+	git checkout 1_p && git merge --no-ff 1_q -m 1_E &&
+	git checkout -b 1_r @~3 && test_commit 1_F &&
+	git checkout 1_p && git merge --no-ff 1_r -m 1_G &&
+	git checkout @^^ && git merge --no-ff 1_p -m 1_H &&
+
+	check_graph <<-\EOF
+	*   1_H
+	|\
+	| *   1_G
+	| |\
+	| | * 1_F
+	| * | 1_E
+	|/| |
+	| * | 1_D
+	* | | 1_C
+	|/ /
+	* / 1_B
+	|/
+	* 1_A
+	EOF
+'
+
+test_expect_success 'log --graph with nested left-skewed merge following normal merge' '
+	git checkout --orphan 2_p &&
+	test_commit 2_A &&
+	test_commit 2_B &&
+	test_commit 2_C &&
+	git checkout -b 2_q @^^ &&
+	test_commit 2_D &&
+	test_commit 2_E &&
+	git checkout -b 2_r @^ && test_commit 2_F &&
+	git checkout 2_q &&
+	git merge --no-ff 2_r -m 2_G &&
+	git merge --no-ff 2_p^ -m 2_H &&
+	git checkout -b 2_s @^^ && git merge --no-ff 2_q -m 2_J &&
+	git checkout 2_p && git merge --no-ff 2_s -m 2_K &&
+
+	check_graph <<-\EOF
+	*   2_K
+	|\
+	| *   2_J
+	| |\
+	| | *   2_H
+	| | |\
+	| | * | 2_G
+	| |/| |
+	| | * | 2_F
+	| * | | 2_E
+	| |/ /
+	| * | 2_D
+	* | | 2_C
+	| |/
+	|/|
+	* | 2_B
+	|/
+	* 2_A
+	EOF
+'
+
+test_expect_success 'log --graph with nested right-skewed merge following left-skewed merge' '
+	git checkout --orphan 3_p &&
+	test_commit 3_A &&
+	git checkout -b 3_q &&
+	test_commit 3_B &&
+	test_commit 3_C &&
+	git checkout -b 3_r @^ &&
+	test_commit 3_D &&
+	git checkout 3_q && git merge --no-ff 3_r -m 3_E &&
+	git checkout 3_p && git merge --no-ff 3_q -m 3_F &&
+	git checkout 3_r && test_commit 3_G &&
+	git checkout 3_p && git merge --no-ff 3_r -m 3_H &&
+	git checkout @^^ && git merge --no-ff 3_p -m 3_J &&
+
+	check_graph <<-\EOF
+	*   3_J
+	|\
+	| *   3_H
+	| |\
+	| | * 3_G
+	| * | 3_F
+	|/| |
+	| * | 3_E
+	| |\|
+	| | * 3_D
+	| * | 3_C
+	| |/
+	| * 3_B
+	|/
+	* 3_A
+	EOF
+'
+
+test_expect_success 'log --graph with right-skewed merge following a left-skewed one' '
+	git checkout --orphan 4_p &&
+	test_commit 4_A &&
+	test_commit 4_B &&
+	test_commit 4_C &&
+	git checkout -b 4_q @^^ && test_commit 4_D &&
+	git checkout -b 4_r 4_p^ && git merge --no-ff 4_q -m 4_E &&
+	git checkout -b 4_s 4_p^^ &&
+	git merge --no-ff 4_r -m 4_F &&
+	git merge --no-ff 4_p -m 4_G &&
+	git checkout @^^ && git merge --no-ff 4_s -m 4_H &&
+
+	check_graph --date-order <<-\EOF
+	*   4_H
+	|\
+	| *   4_G
+	| |\
+	| * | 4_F
+	|/| |
+	| * |   4_E
+	| |\ \
+	| | * | 4_D
+	| |/ /
+	|/| |
+	| | * 4_C
+	| |/
+	| * 4_B
+	|/
+	* 4_A
+	EOF
+'
+
+test_expect_success 'log --graph with octopus merge with column joining its penultimate parent' '
+	git checkout --orphan 5_p &&
+	test_commit 5_A &&
+	git branch 5_q &&
+	git branch 5_r &&
+	test_commit 5_B &&
+	git checkout 5_q && test_commit 5_C &&
+	git checkout 5_r && test_commit 5_D &&
+	git checkout 5_p &&
+	git merge --no-ff 5_q 5_r -m 5_E &&
+	git checkout 5_q && test_commit 5_F &&
+	git checkout -b 5_s 5_p^ &&
+	git merge --no-ff 5_p 5_q -m 5_G &&
+	git checkout 5_r &&
+	git merge --no-ff 5_s -m 5_H &&
+
+	check_graph <<-\EOF
+	*   5_H
+	|\
+	| *-.   5_G
+	| |\ \
+	| | | * 5_F
+	| | * |   5_E
+	| |/|\ \
+	| |_|/ /
+	|/| | /
+	| | |/
+	* | | 5_D
+	| | * 5_C
+	| |/
+	|/|
+	| * 5_B
+	|/
+	* 5_A
+	EOF
+'
+
+test_expect_success 'log --graph with multiple tips' '
+	git checkout --orphan 6_1 &&
+	test_commit 6_A &&
+	git branch 6_2 &&
+	git branch 6_4 &&
+	test_commit 6_B &&
+	git branch 6_3 &&
+	test_commit 6_C &&
+	git checkout 6_2 && test_commit 6_D &&
+	git checkout 6_3 && test_commit 6_E &&
+	git checkout -b 6_5 6_1 &&
+	git merge --no-ff 6_2 -m 6_F &&
+	git checkout 6_4 && test_commit 6_G &&
+	git checkout 6_3 &&
+	git merge --no-ff 6_4 -m 6_H &&
+	git checkout 6_1 &&
+	git merge --no-ff 6_2 -m 6_I &&
+
+	check_graph 6_1 6_3 6_5 <<-\EOF
+	*   6_I
+	|\
+	| | *   6_H
+	| | |\
+	| | | * 6_G
+	| | * | 6_E
+	| | | | * 6_F
+	| |_|_|/|
+	|/| | |/
+	| | |/|
+	| |/| |
+	| * | | 6_D
+	| | |/
+	| |/|
+	* | | 6_C
+	| |/
+	|/|
+	* | 6_B
+	|/
+	* 6_A
+	EOF
+'
+
+test_expect_success 'log --graph with multiple tips and colors' '
+	test_config log.graphColors red,green,yellow,blue,magenta,cyan &&
+	cat >expect.colors <<-\EOF &&
+	*   6_I
+	<RED>|<RESET><GREEN>\<RESET>
+	<RED>|<RESET> <GREEN>|<RESET> *   6_H
+	<RED>|<RESET> <GREEN>|<RESET> <YELLOW>|<RESET><BLUE>\<RESET>
+	<RED>|<RESET> <GREEN>|<RESET> <YELLOW>|<RESET> * 6_G
+	<RED>|<RESET> <GREEN>|<RESET> <YELLOW>|<RESET> <BLUE>|<RESET> * 6_F
+	<RED>|<RESET> <GREEN>|<RESET><RED>_<RESET><YELLOW>|<RESET><RED>_<RESET><BLUE>|<RESET><RED>/<RESET><GREEN>|<RESET>
+	<RED>|<RESET><RED>/<RESET><GREEN>|<RESET> <YELLOW>|<RESET> <BLUE>|<RESET><GREEN>/<RESET>
+	<RED>|<RESET> <GREEN>|<RESET> <YELLOW>|<RESET><GREEN>/<RESET><BLUE>|<RESET>
+	<RED>|<RESET> <GREEN>|<RESET><GREEN>/<RESET><YELLOW>|<RESET> <BLUE>|<RESET>
+	<RED>|<RESET> <GREEN>|<RESET> * <BLUE>|<RESET> 6_E
+	<RED>|<RESET> * <CYAN>|<RESET> <BLUE>|<RESET> 6_D
+	<RED>|<RESET> <BLUE>|<RESET> <CYAN>|<RESET><BLUE>/<RESET>
+	<RED>|<RESET> <BLUE>|<RESET><BLUE>/<RESET><CYAN>|<RESET>
+	* <BLUE>|<RESET> <CYAN>|<RESET> 6_C
+	<CYAN>|<RESET> <BLUE>|<RESET><CYAN>/<RESET>
+	<CYAN>|<RESET><CYAN>/<RESET><BLUE>|<RESET>
+	* <BLUE>|<RESET> 6_B
+	<BLUE>|<RESET><BLUE>/<RESET>
+	* 6_A
+	EOF
+	lib_test_cmp_colored_graph --date-order --pretty=tformat:%s 6_1 6_3 6_5
+'
+
+test_expect_success 'log --graph with multiple tips' '
+	git checkout --orphan 7_1 &&
+	test_commit 7_A &&
+	test_commit 7_B &&
+	test_commit 7_C &&
+	git checkout -b 7_2 7_1~2 &&
+	test_commit 7_D &&
+	test_commit 7_E &&
+	git checkout -b 7_3 7_1~1 &&
+	test_commit 7_F &&
+	test_commit 7_G &&
+	git checkout -b 7_4 7_2~1 &&
+	test_commit 7_H &&
+	git checkout -b 7_5 7_1~2 &&
+	test_commit 7_I &&
+	git checkout -b 7_6 7_3~1 &&
+	test_commit 7_J &&
+	git checkout -b M_1 7_1 &&
+	git merge --no-ff 7_2 -m 7_M1 &&
+	git checkout -b M_3 7_3 &&
+	git merge --no-ff 7_4 -m 7_M2 &&
+	git checkout -b M_5 7_5 &&
+	git merge --no-ff 7_6 -m 7_M3 &&
+	git checkout -b M_7 7_1 &&
+	git merge --no-ff 7_2 7_3 -m 7_M4 &&
+
+	check_graph M_1 M_3 M_5 M_7 <<-\EOF
+	*   7_M1
+	|\
+	| | *   7_M2
+	| | |\
+	| | | * 7_H
+	| | | | *   7_M3
+	| | | | |\
+	| | | | | * 7_J
+	| | | | * | 7_I
+	| | | | | | *   7_M4
+	| |_|_|_|_|/|\
+	|/| | | | |/ /
+	| | |_|_|/| /
+	| |/| | | |/
+	| | | |_|/|
+	| | |/| | |
+	| | * | | | 7_G
+	| | | |_|/
+	| | |/| |
+	| | * | | 7_F
+	| * | | | 7_E
+	| | |/ /
+	| |/| |
+	| * | | 7_D
+	| | |/
+	| |/|
+	* | | 7_C
+	| |/
+	|/|
+	* | 7_B
+	|/
+	* 7_A
+	EOF
+'
+
+test_done