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/t5150-request-pull.sh

@@ -4,6 +4,12 @@ test_description='Test workflows involving pull request.'
 
 . ./test-lib.sh
 
+if ! test_have_prereq PERL
+then
+	skip_all='skipping request-pull tests, perl not available'
+	test_done
+fi
+
 test_expect_success 'setup' '
 
 	git init --bare upstream.git &&
@@ -144,7 +150,6 @@ test_expect_success 'pull request after push' '
 		git request-pull initial origin master:for-upstream >../request
 	) &&
 	sed -nf read-request.sed <request >digest &&
-	cat digest &&
 	{
 		read task &&
 		read repository &&
@@ -173,7 +178,6 @@ test_expect_success 'request asks HEAD to be pulled' '
 		git request-pull initial "$downstream_url" >../request
 	) &&
 	sed -nf read-request.sed <request >digest &&
-	cat digest &&
 	{
 		read task &&
 		read repository &&