[PATCH] config: don't segfault when given --path with a missing value

["Carlos Martín Nieto" <cmn@elego.de>]

When given a variable without a value, such as '[section] var' and
asking git-config to treat it as a path, git_config_pathname returns
an error and doesn't modify its output parameter. show_config assumes
that the call is always successful and sets a variable to indicate
that vptr should be freed. In case of an error however, trying to do
this will cause the program to be killed, as it's pointing to memory
in the stack.

Set the must_free_vptr flag depending on the return value of
git_config_pathname so it's accurate.
---
 builtin/config.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/builtin/config.c b/builtin/config.c
index 442ccc2..60220d5 100644
--- a/builtin/config.c
+++ b/builtin/config.c
@@ -129,8 +129,7 @@ static int show_config(const char *key_, const char *value_, void *cb)
 		else
 			sprintf(value, "%d", v);
 	} else if (types == TYPE_PATH) {
-		git_config_pathname(&vptr, key_, value_);
-		must_free_vptr = 1;
+		must_free_vptr = !git_config_pathname(&vptr, key_, value_);
 	} else if (value_) {
 		vptr = value_;
 	} else {
-- 
1.8.0.316.g291341c