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/t4108-apply-threeway.sh

@@ -4,23 +4,17 @@ test_description='git apply --3way'
 
 . ./test-lib.sh
 
-create_file () {
-	for i
-	do
-		echo "$i"
-	done
-}
-
-sanitize_conflicted_diff () {
+print_sanitized_conflicted_diff () {
+	git diff HEAD >diff.raw &&
 	sed -e '
 		/^index /d
-		s/^\(+[<>][<>][<>][<>]*\) .*/\1/
-	'
+		s/^\(+[<>|][<>|][<>|][<>|]*\) .*/\1/
+	' diff.raw
 }
 
 test_expect_success setup '
 	test_tick &&
-	create_file >one 1 2 3 4 5 6 7 &&
+	test_write_lines 1 2 3 4 5 6 7 >one &&
 	cat one >two &&
 	git add one two &&
 	git commit -m initial &&
@@ -28,13 +22,13 @@ test_expect_success setup '
 	git branch side &&
 
 	test_tick &&
-	create_file >one 1 two 3 4 5 six 7 &&
-	create_file >two 1 two 3 4 5 6 7 &&
+	test_write_lines 1 two 3 4 5 six 7 >one &&
+	test_write_lines 1 two 3 4 5 6 7 >two &&
 	git commit -a -m master &&
 
 	git checkout side &&
-	create_file >one 1 2 3 4 five 6 7 &&
-	create_file >two 1 2 3 4 five 6 7 &&
+	test_write_lines 1 2 3 4 five 6 7 >one &&
+	test_write_lines 1 2 3 4 five 6 7 >two &&
 	git commit -a -m side &&
 
 	git checkout master
@@ -52,7 +46,7 @@ test_expect_success 'apply without --3way' '
 	git diff-index --exit-code --cached HEAD
 '
 
-test_expect_success 'apply with --3way' '
+test_apply_with_3way () {
 	# Merging side should be similar to applying this patch
 	git diff ...side >P.diff &&
 
@@ -61,22 +55,31 @@ test_expect_success 'apply with --3way' '
 	git checkout master^0 &&
 	test_must_fail git merge --no-commit side &&
 	git ls-files -s >expect.ls &&
-	git diff HEAD | sanitize_conflicted_diff >expect.diff &&
+	print_sanitized_conflicted_diff >expect.diff &&
 
 	# should fail to apply
 	git reset --hard &&
 	git checkout master^0 &&
 	test_must_fail git apply --index --3way P.diff &&
 	git ls-files -s >actual.ls &&
-	git diff HEAD | sanitize_conflicted_diff >actual.diff &&
+	print_sanitized_conflicted_diff >actual.diff &&
 
 	# The result should resemble the corresponding merge
 	test_cmp expect.ls actual.ls &&
 	test_cmp expect.diff actual.diff
+}
+
+test_expect_success 'apply with --3way' '
+	test_apply_with_3way
+'
+
+test_expect_success 'apply with --3way with merge.conflictStyle = diff3' '
+	test_config merge.conflictStyle diff3 &&
+	test_apply_with_3way
 '
 
 test_expect_success 'apply with --3way with rerere enabled' '
-	git config rerere.enabled true &&
+	test_config rerere.enabled true &&
 
 	# Merging side should be similar to applying this patch
 	git diff ...side >P.diff &&
@@ -87,7 +90,7 @@ test_expect_success 'apply with --3way with rerere enabled' '
 	test_must_fail git merge --no-commit side &&
 
 	# Manually resolve and record the resolution
-	create_file 1 two 3 4 five six 7 >one &&
+	test_write_lines 1 two 3 4 five six 7 >one &&
 	git rerere &&
 	cat one >expect &&
 
@@ -104,14 +107,14 @@ test_expect_success 'apply -3 with add/add conflict setup' '
 	git reset --hard &&
 
 	git checkout -b adder &&
-	create_file 1 2 3 4 5 6 7 >three &&
-	create_file 1 2 3 4 5 6 7 >four &&
+	test_write_lines 1 2 3 4 5 6 7 >three &&
+	test_write_lines 1 2 3 4 5 6 7 >four &&
 	git add three four &&
 	git commit -m "add three and four" &&
 
 	git checkout -b another adder^ &&
-	create_file 1 2 3 4 5 6 7 >three &&
-	create_file 1 2 3 four 5 6 7 >four &&
+	test_write_lines 1 2 3 4 5 6 7 >three &&
+	test_write_lines 1 2 3 four 5 6 7 >four &&
 	git add three four &&
 	git commit -m "add three and four" &&
 
@@ -121,7 +124,7 @@ test_expect_success 'apply -3 with add/add conflict setup' '
 	git checkout adder^0 &&
 	test_must_fail git merge --no-commit another &&
 	git ls-files -s >expect.ls &&
-	git diff HEAD | sanitize_conflicted_diff >expect.diff
+	print_sanitized_conflicted_diff >expect.diff
 '
 
 test_expect_success 'apply -3 with add/add conflict' '
@@ -131,7 +134,7 @@ test_expect_success 'apply -3 with add/add conflict' '
 	test_must_fail git apply --index --3way P.diff &&
 	# ... and leave conflicts in the index and in the working tree
 	git ls-files -s >actual.ls &&
-	git diff HEAD | sanitize_conflicted_diff >actual.diff &&
+	print_sanitized_conflicted_diff >actual.diff &&
 
 	# The result should resemble the corresponding merge
 	test_cmp expect.ls actual.ls &&