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, 41 insertions, 22 deletions

diff --git a/third_party/git/Documentation/git-commit-graph.txt b/third_party/git/Documentation/git-commit-graph.txt
index eb5e7865f0..de6b6de230 100644
--- a/third_party/git/Documentation/git-commit-graph.txt
+++ b/third_party/git/Documentation/git-commit-graph.txt
@@ -9,9 +9,8 @@ git-commit-graph - Write and verify Git commit-graph files
 SYNOPSIS
 --------
 [verse]
-'git commit-graph read' [--object-dir <dir>]
-'git commit-graph verify' [--object-dir <dir>] [--shallow]
-'git commit-graph write' <options> [--object-dir <dir>]
+'git commit-graph verify' [--object-dir <dir>] [--shallow] [--[no-]progress]
+'git commit-graph write' <options> [--object-dir <dir>] [--[no-]progress]
 
 
 DESCRIPTION
@@ -27,8 +26,14 @@ OPTIONS
 	file. This parameter exists to specify the location of an alternate
 	that only has the objects directory, not a full `.git` directory. The
 	commit-graph file is expected to be in the `<dir>/info` directory and
-	the packfiles are expected to be in `<dir>/pack`.
+	the packfiles are expected to be in `<dir>/pack`. If the directory
+	could not be made into an absolute path, or does not match any known
+	object directory, `git commit-graph ...` will exit with non-zero
+	status.
 
+--[no-]progress::
+	Turn progress on/off explicitly. If neither is specified, progress is
+	shown if standard error is connected to a terminal.
 
 COMMANDS
 --------
@@ -42,8 +47,10 @@ with `--stdin-commits` or `--reachable`.)
 +
 With the `--stdin-commits` option, generate the new commit graph by
 walking commits starting at the commits specified in stdin as a list
-of OIDs in hex, one OID per line. (Cannot be combined with
-`--stdin-packs` or `--reachable`.)
+of OIDs in hex, one OID per line. OIDs that resolve to non-commits
+(either directly, or by peeling tags) are silently ignored. OIDs that
+are malformed, or do not exist generate an error. (Cannot be combined
+with `--stdin-packs` or `--reachable`.)
 +
 With the `--reachable` option, generate the new commit graph by walking
 commits starting at all refs. (Cannot be combined with `--stdin-commits`
@@ -52,11 +59,34 @@ or `--stdin-packs`.)
 With the `--append` option, include all commits that are present in the
 existing commit-graph file.
 +
-With the `--split` option, write the commit-graph as a chain of multiple
-commit-graph files stored in `<dir>/info/commit-graphs`. The new commits
-not already in the commit-graph are added in a new "tip" file. This file
-is merged with the existing file if the following merge conditions are
-met:
+With the `--changed-paths` option, compute and write information about the
+paths changed between a commit and its first parent. This operation can
+take a while on large repositories. It provides significant performance gains
+for getting history of a directory or a file with `git log -- <path>`. If
+this option is given, future commit-graph writes will automatically assume
+that this option was intended. Use `--no-changed-paths` to stop storing this
+data.
++
+With the `--max-new-filters=<n>` option, generate at most `n` new Bloom
+filters (if `--changed-paths` is specified). If `n` is `-1`, no limit is
+enforced. Only commits present in the new layer count against this
+limit. To retroactively compute Bloom filters over earlier layers, it is
+advised to use `--split=replace`.  Overrides the `commitGraph.maxNewFilters`
+configuration.
++
+With the `--split[=<strategy>]` option, write the commit-graph as a
+chain of multiple commit-graph files stored in
+`<dir>/info/commit-graphs`. Commit-graph layers are merged based on the
+strategy and other splitting options. The new commits not already in the
+commit-graph are added in a new "tip" file. This file is merged with the
+existing file if the following merge conditions are met:
++
+* If `--split=no-merge` is specified, a merge is never performed, and
+the remaining options are ignored. `--split=replace` overwrites the
+existing chain with a new one. A bare `--split` defers to the remaining
+options. (Note that merging a chain of commit graphs replaces the
+existing chain with a length-1 chain where the first and only
+incremental holds the entire graph).
 +
 * If `--size-multiple=<X>` is not specified, let `X` equal 2. If the new
 tip file would have `N` commits and the previous tip has `M` commits and
@@ -71,11 +101,6 @@ Finally, if `--expire-time=<datetime>` is not specified, let `datetime`
 be the current time. After writing the split commit-graph, delete all
 unused commit-graph whose modified times are older than `datetime`.
 
-'read'::
-
-Read the commit-graph file and output basic details about it.
-Used for debugging purposes.
-
 'verify'::
 
 Read the commit-graph file and verify its contents against the object
@@ -115,12 +140,6 @@ $ git show-ref -s | git commit-graph write --stdin-commits
 $ git rev-parse HEAD | git commit-graph write --stdin-commits --append
 ------------------------------------------------
 
-* Read basic information from the commit-graph file.
-+
-------------------------------------------------
-$ git commit-graph read
-------------------------------------------------
-
 
 GIT
 ---