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, 21 insertions, 14 deletions

diff --git a/third_party/git/Documentation/SubmittingPatches b/third_party/git/Documentation/SubmittingPatches
index 6d589e118c17..291b61e26213 100644
--- a/third_party/git/Documentation/SubmittingPatches
+++ b/third_party/git/Documentation/SubmittingPatches
@@ -3,8 +3,9 @@ Submitting Patches
 
 == Guidelines
 
-Here are some guidelines for people who want to contribute their code
-to this software.
+Here are some guidelines for people who want to contribute their code to this
+software. There is also a link:MyFirstContribution.html[step-by-step tutorial]
+available which covers many of these same guidelines.
 
 [[base-branch]]
 === Decide what to base your work on.
@@ -18,7 +19,7 @@ change is relevant to.
   base your work on the tip of the topic.
 
 * A new feature should be based on `master` in general. If the new
-  feature depends on a topic that is in `pu`, but not in `master`,
+  feature depends on a topic that is in `seen`, but not in `master`,
   base your work on the tip of that topic.
 
 * Corrections and enhancements to a topic not yet in `master` should
@@ -27,7 +28,7 @@ change is relevant to.
   into the series.
 
 * In the exceptional case that a new feature depends on several topics
-  not in `master`, start working on `next` or `pu` privately and send
+  not in `master`, start working on `next` or `seen` privately and send
   out patches for discussion. Before the final merge, you may have to
   wait until some of the dependent topics graduate to `master`, and
   rebase your work.
@@ -37,7 +38,7 @@ change is relevant to.
   these parts should be based on their trees.
 
 To find the tip of a topic branch, run `git log --first-parent
-master..pu` and look for the merge commit. The second parent of this
+master..seen` and look for the merge commit. The second parent of this
 commit is the tip of the topic branch.
 
 [[separate-commits]]
@@ -142,19 +143,25 @@ archive, summarize the relevant points of the discussion.
 
 [[commit-reference]]
 If you want to reference a previous commit in the history of a stable
-branch, use the format "abbreviated sha1 (subject, date)",
-with the subject enclosed in a pair of double-quotes, like this:
+branch, use the format "abbreviated hash (subject, date)", like this:
 
 ....
-	Commit f86a374 ("pack-bitmap.c: fix a memleak", 2015-03-30)
+	Commit f86a374 (pack-bitmap.c: fix a memleak, 2015-03-30)
 	noticed that ...
 ....
 
 The "Copy commit summary" command of gitk can be used to obtain this
-format, or this invocation of `git show`:
+format (with the subject enclosed in a pair of double-quotes), or this
+invocation of `git show`:
 
 ....
-	git show -s --date=short --pretty='format:%h ("%s", %ad)' <commit>
+	git show -s --pretty=reference <commit>
+....
+
+or, on an older version of Git without support for --pretty=reference:
+
+....
+	git show -s --date=short --pretty='format:%h (%s, %ad)' <commit>
 ....
 
 [[git-tools]]
@@ -372,9 +379,9 @@ such as "Thanks-to:", "Based-on-patch-by:", or "Mentored-by:".
 Some parts of the system have dedicated maintainers with their own
 repositories.
 
-- `git-gui/` comes from git-gui project, maintained by Pat Thoyts:
+- `git-gui/` comes from git-gui project, maintained by Pratyush Yadav:
 
-	git://repo.or.cz/git-gui.git
+	https://github.com/prati0100/git-gui.git
 
 - `gitk-git/` comes from Paul Mackerras's gitk project:
 
@@ -417,7 +424,7 @@ help you find out who they are.
   and cooked further and eventually graduates to `master`.
 
 In any time between the (2)-(3) cycle, the maintainer may pick it up
-from the list and queue it to `pu`, in order to make it easier for
+from the list and queue it to `seen`, in order to make it easier for
 people play with it without having to pick up and apply the patch to
 their trees themselves.
 
@@ -428,7 +435,7 @@ their trees themselves.
   master. `git pull --rebase` will automatically skip already-applied
   patches, and will let you know. This works only if you rebase on top
   of the branch in which your patch has been merged (i.e. it will not
-  tell you if your patch is merged in pu if you rebase on top of
+  tell you if your patch is merged in `seen` if you rebase on top of
   master).
 
 * Read the Git mailing list, the maintainer regularly posts messages