[PATCH] Fix strcat() on uninitialized memory

[Johannes Schindelin <Johannes.Schindelin@gmx.de>]

Under certain circumstances, this bug would trigger a buffer overflow
error with libc, and fail test 5516.

Strbufs would have avoided the issue.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 builtin/receive-pack.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/builtin/receive-pack.c b/builtin/receive-pack.c
index 05071c3..1644424 100644
--- a/builtin/receive-pack.c
+++ b/builtin/receive-pack.c
@@ -569,9 +569,9 @@ static void check_aliased_update(struct command *cmd, struct string_list *list)
 	dst_cmd->skip_update = 1;
 
 	strcpy(cmd_oldh, find_unique_abbrev(cmd->old_sha1, DEFAULT_ABBREV));
-	strcat(cmd_newh, find_unique_abbrev(cmd->new_sha1, DEFAULT_ABBREV));
+	strcpy(cmd_newh, find_unique_abbrev(cmd->new_sha1, DEFAULT_ABBREV));
 	strcpy(dst_oldh, find_unique_abbrev(dst_cmd->old_sha1, DEFAULT_ABBREV));
-	strcat(dst_newh, find_unique_abbrev(dst_cmd->new_sha1, DEFAULT_ABBREV));
+	strcpy(dst_newh, find_unique_abbrev(dst_cmd->new_sha1, DEFAULT_ABBREV));
 	rp_error("refusing inconsistent update between symref '%s' (%s..%s) and"
 		 " its target '%s' (%s..%s)",
 		 cmd->ref_name, cmd_oldh, cmd_newh,
-- 
1.7.1.msysgit.0.2.g2fefc8