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/t5607-clone-bundle.sh

@@ -4,6 +4,10 @@ test_description='some bundle related tests'
 . ./test-lib.sh
 
 test_expect_success 'setup' '
+	test_oid_cache <<-EOF &&
+	version sha1:2
+	version sha256:3
+	EOF
 	test_commit initial &&
 	test_tick &&
 	git tag -m tag tag &&
@@ -16,7 +20,7 @@ test_expect_success 'setup' '
 
 test_expect_success '"verify" needs a worktree' '
 	git bundle create tip.bundle -1 master &&
-	test_must_fail nongit git bundle verify ../tip.bundle 2>err &&
+	nongit test_must_fail git bundle verify ../tip.bundle 2>err &&
 	test_i18ngrep "need a repository" err
 '
 
@@ -64,7 +68,7 @@ test_expect_success 'ridiculously long subject in boundary' '
 	test -s heads &&
 	git fetch long-subject-bundle.bdl &&
 	sed -n "/^-/{p;q;}" long-subject-bundle.bdl >boundary &&
-	grep "^-[0-9a-f]\\{40\\} " boundary
+	grep "^-$OID_REGEX " boundary
 '
 
 test_expect_success 'prerequisites with an empty commit message' '
@@ -83,4 +87,42 @@ test_expect_success 'failed bundle creation does not leave cruft' '
 	test_path_is_missing fail.bundle.lock
 '
 
+test_expect_success 'fetch SHA-1 from bundle' '
+	test_create_repo foo &&
+	test_commit -C foo x &&
+	git -C foo bundle create tip.bundle -1 master &&
+	git -C foo rev-parse HEAD >hash &&
+
+	# Exercise to ensure that fetching a SHA-1 from a bundle works with no
+	# errors
+	git fetch --no-tags foo/tip.bundle "$(cat hash)"
+'
+
+test_expect_success 'git bundle uses expected default format' '
+	git bundle create bundle HEAD^.. &&
+	head -n1 bundle | grep "^# v$(test_oid version) git bundle$"
+'
+
+test_expect_success 'git bundle v3 has expected contents' '
+	git branch side HEAD &&
+	git bundle create --version=3 bundle HEAD^..side &&
+	head -n2 bundle >actual &&
+	cat >expect <<-EOF &&
+	# v3 git bundle
+	@object-format=$(test_oid algo)
+	EOF
+	test_cmp expect actual &&
+	git bundle verify bundle
+'
+
+test_expect_success 'git bundle v3 rejects unknown capabilities' '
+	cat >new <<-EOF &&
+	# v3 git bundle
+	@object-format=$(test_oid algo)
+	@unknown=silly
+	EOF
+	test_must_fail git bundle verify new 2>output &&
+	test_i18ngrep "unknown capability .unknown=silly." output
+'
+
 test_done