[PATCH v3] git: make "git -C '' <cmd>" not to barf

[Karthik Nayak <karthik.188@gmail.com>]

It now acts like "cd ''" and does not barf and treats
it as a no-op. This is useful if a caller function
does not want to change directory and hence gives no
path value, which would have generally caused git to
output an undesired error message.

Included a simple test to check the same, as suggested
by Junio.

Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
---
 git.c            | 12 ++++++++----
 t/t0056-git-C.sh |  8 ++++++++
 2 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/git.c b/git.c
index 8c7ee9c..d734afa 100644
--- a/git.c
+++ b/git.c
@@ -204,10 +204,14 @@ static int handle_options(const char ***argv, int *argc, int *envchanged)
 				fprintf(stderr, "No directory given for -C.\n" );
 				usage(git_usage_string);
 			}
-			if (chdir((*argv)[1]))
-				die_errno("Cannot change to '%s'", (*argv)[1]);
-			if (envchanged)
-				*envchanged = 1;
+			if (*((*argv)[1]) == 0)
+				; /* DO not change directory if no directory is given*/
+			else {
+				if (chdir((*argv)[1]))
+					die_errno("Cannot change to '%s'", (*argv)[1]);
+				if (envchanged)
+					*envchanged = 1;
+			}
 			(*argv)++;
 			(*argc)--;
 		} else {
diff --git a/t/t0056-git-C.sh b/t/t0056-git-C.sh
index 99c0377..a6b52f1 100755
--- a/t/t0056-git-C.sh
+++ b/t/t0056-git-C.sh
@@ -14,6 +14,14 @@ test_expect_success '"git -C <path>" runs git from the directory <path>' '
 	test_cmp expected actual
 '
 
+test_expect_success '"git -C <path>" with an empty <path> is a no-op' '
+	mkdir -p dir1/subdir &&
+	cd dir1/subdir &&
+	git -C "" rev-parse --show-prefix >actual &&
+	echo subdir/ >expect
+	test_cmp expect actual
+'
+
 test_expect_success 'Multiple -C options: "-C dir1 -C dir2" is equivalent to "-C dir1/dir2"' '
 	test_create_repo dir1/dir2 &&
 	echo 1 >dir1/dir2/b.txt &&
-- 
2.3.1.167.g7f4ba4b.dirty