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/t5601-clone.sh

@@ -271,7 +271,9 @@ test_expect_success 'fetch from gitfile parent' '
 
 test_expect_success 'clone separate gitdir where target already exists' '
 	rm -rf dst &&
-	test_must_fail git clone --separate-git-dir realgitdir src dst
+	echo foo=bar >>realgitdir/config &&
+	test_must_fail git clone --separate-git-dir realgitdir src dst &&
+	grep foo=bar realgitdir/config
 '
 
 test_expect_success 'clone --reference from original' '
@@ -434,7 +436,6 @@ test_expect_success 'double quoted plink.exe in GIT_SSH_COMMAND' '
 	expect_ssh "-v -P 123" myhost src
 '
 
-SQ="'"
 test_expect_success 'single quoted plink.exe in GIT_SSH_COMMAND' '
 	copy_ssh_wrapper_as "$TRASH_DIRECTORY/plink.exe" &&
 	GIT_SSH_COMMAND="$SQ$TRASH_DIRECTORY/plink.exe$SQ -v" \
@@ -630,16 +631,30 @@ test_expect_success CASE_INSENSITIVE_FS 'colliding file detection' '
 	test_i18ngrep "the following paths have collided" icasefs/warning
 '
 
+test_expect_success 'clone with GIT_DEFAULT_HASH' '
+	(
+		sane_unset GIT_DEFAULT_HASH &&
+		git init --object-format=sha1 test-sha1 &&
+		git init --object-format=sha256 test-sha256
+	) &&
+	test_commit -C test-sha1 foo &&
+	test_commit -C test-sha256 foo &&
+	GIT_DEFAULT_HASH=sha1 git clone test-sha256 test-clone-sha256 &&
+	GIT_DEFAULT_HASH=sha256 git clone test-sha1 test-clone-sha1 &&
+	git -C test-clone-sha1 status &&
+	git -C test-clone-sha256 status
+'
+
 partial_clone_server () {
 	       SERVER="$1" &&
 
 	rm -rf "$SERVER" client &&
 	test_create_repo "$SERVER" &&
 	test_commit -C "$SERVER" one &&
-	HASH1=$(git hash-object "$SERVER/one.t") &&
+	HASH1=$(git -C "$SERVER" hash-object one.t) &&
 	git -C "$SERVER" revert HEAD &&
 	test_commit -C "$SERVER" two &&
-	HASH2=$(git hash-object "$SERVER/two.t") &&
+	HASH2=$(git -C "$SERVER" hash-object two.t) &&
 	test_config -C "$SERVER" uploadpack.allowfilter 1 &&
 	test_config -C "$SERVER" uploadpack.allowanysha1inwant 1
 }
@@ -654,7 +669,8 @@ partial_clone () {
 	git -C client fsck &&
 
 	# Ensure that unneeded blobs are not inadvertently fetched.
-	test_config -C client extensions.partialclone "not a remote" &&
+	test_config -C client remote.origin.promisor "false" &&
+	git -C client config --unset remote.origin.partialclonefilter &&
 	test_must_fail git -C client cat-file -e "$HASH1" &&
 
 	# But this blob was fetched, because clone performs an initial checkout
@@ -667,7 +683,8 @@ test_expect_success 'partial clone' '
 
 test_expect_success 'partial clone with -o' '
 	partial_clone_server server &&
-	git clone -o blah --filter=blob:limit=0 "file://$(pwd)/server" client
+	git clone -o blah --filter=blob:limit=0 "file://$(pwd)/server" client &&
+	test_cmp_config -C client "blob:limit=0" --get-all remote.blah.partialclonefilter
 '
 
 test_expect_success 'partial clone: warn if server does not support object filtering' '
@@ -702,7 +719,7 @@ test_expect_success 'batch missing blob request during checkout' '
 	# Ensure that there is only one negotiation by checking that there is
 	# only "done" line sent. ("done" marks the end of negotiation.)
 	GIT_TRACE_PACKET="$(pwd)/trace" git -C client checkout HEAD^ &&
-	grep "git> done" trace >done_lines &&
+	grep "fetch> done" trace >done_lines &&
 	test_line_count = 1 done_lines
 '
 
@@ -739,4 +756,7 @@ test_expect_success 'partial clone using HTTP' '
 	partial_clone "$HTTPD_DOCUMENT_ROOT_PATH/server" "$HTTPD_URL/smart/server"
 '
 
+# DO NOT add non-httpd-specific tests here, because the last part of this
+# test script is only executed when httpd is available and enabled.
+
 test_done