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

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

third_party/git/t/t9351-fast-export-anonymize.sh

@@ -6,15 +6,24 @@ test_description='basic tests for fast-export --anonymize'
 test_expect_success 'setup simple repo' '
 	test_commit base &&
 	test_commit foo &&
+	test_commit retain-me &&
 	git checkout -b other HEAD^ &&
 	mkdir subdir &&
 	test_commit subdir/bar &&
 	test_commit subdir/xyzzy &&
+	fake_commit=$(echo $ZERO_OID | sed s/0/a/) &&
+	git update-index --add --cacheinfo 160000,$fake_commit,link1 &&
+	git update-index --add --cacheinfo 160000,$fake_commit,link2 &&
+	git commit -m "add gitlink" &&
 	git tag -m "annotated tag" mytag
 '
 
 test_expect_success 'export anonymized stream' '
-	git fast-export --anonymize --all >stream
+	git fast-export --anonymize --all \
+		--anonymize-map=retain-me \
+		--anonymize-map=xyzzy:custom-name \
+		--anonymize-map=other \
+		>stream
 '
 
 # this also covers commit messages
@@ -26,12 +35,23 @@ test_expect_success 'stream omits path names' '
 	! grep xyzzy stream
 '
 
-test_expect_success 'stream allows master as refname' '
-	grep master stream
+test_expect_success 'stream contains user-specified names' '
+	grep retain-me stream &&
+	grep custom-name stream
+'
+
+test_expect_success 'stream omits gitlink oids' '
+	# avoid relying on the whole oid to remain hash-agnostic; this is
+	# plenty to be unique within our test case
+	! grep a000000000000000000 stream
+'
+
+test_expect_success 'stream retains other as refname' '
+	grep other stream
 '
 
 test_expect_success 'stream omits other refnames' '
-	! grep other stream &&
+	! grep master stream &&
 	! grep mytag stream
 '
 
@@ -57,7 +77,8 @@ test_expect_success 'import stream to new repository' '
 test_expect_success 'result has two branches' '
 	git for-each-ref --format="%(refname)" refs/heads >branches &&
 	test_line_count = 2 branches &&
-	other_branch=$(grep -v refs/heads/master branches)
+	other_branch=refs/heads/other &&
+	main_branch=$(grep -v $other_branch branches)
 '
 
 test_expect_success 'repo has original shape and timestamps' '
@@ -65,34 +86,35 @@ test_expect_success 'repo has original shape and timestamps' '
 		git log --format="%m %ct" --left-right --boundary "$@"
 	} &&
 	(cd .. && shape master...other) >expect &&
-	shape master...$other_branch >actual &&
+	shape $main_branch...$other_branch >actual &&
 	test_cmp expect actual
 '
 
 test_expect_success 'root tree has original shape' '
 	# the output entries are not necessarily in the same
-	# order, but we know at least that we will have one tree
-	# and one blob, so just check the sorted order
-	cat >expect <<-\EOF &&
-	blob
-	tree
-	EOF
+	# order, but we should at least have the same set of
+	# object types.
+	git -C .. ls-tree HEAD >orig-root &&
+	cut -d" " -f2 <orig-root | sort >expect &&
 	git ls-tree $other_branch >root &&
 	cut -d" " -f2 <root | sort >actual &&
 	test_cmp expect actual
 '
 
 test_expect_success 'paths in subdir ended up in one tree' '
-	cat >expect <<-\EOF &&
-	blob
-	blob
-	EOF
+	git -C .. ls-tree other:subdir >orig-subdir &&
+	cut -d" " -f2 <orig-subdir | sort >expect &&
 	tree=$(grep tree root | cut -f2) &&
 	git ls-tree $other_branch:$tree >tree &&
 	cut -d" " -f2 <tree >actual &&
 	test_cmp expect actual
 '
 
+test_expect_success 'identical gitlinks got identical oid' '
+	awk "/commit/ { print \$3 }" <root | sort -u >commits &&
+	test_line_count = 1 commits
+'
+
 test_expect_success 'tag points to branch tip' '
 	git rev-parse $other_branch >expect &&
 	git for-each-ref --format="%(*objectname)" | grep . >actual &&