repo-config: give value_ a sane default so regexec won't segfault

Signed-off-by: Jonas Fonseca <fonseca@diku.dk>
Signed-off-by: Junio C Hamano <junkio@cox.net>

repo-config.c

@@ -14,6 +14,9 @@ static enum { T_RAW, T_INT, T_BOOL } type = T_RAW;
 
 static int show_config(const char* key_, const char* value_)
 {
+	if (value_ == NULL)
+		value_ = "";
+
 	if (!strcmp(key_, key) &&
 			(regexp == NULL ||
 			 (do_not_match ^
@@ -35,7 +38,7 @@ static int show_config(const char* key_, const char* value_)
 			sprintf(value, "%s", git_config_bool(key_, value_)
 					     ? "true" : "false");
 		} else {
-			value = strdup(value_ ? value_ : "");
+			value = strdup(value_);
 		}
 		seen++;
 	}

t/t1300-repo-config.sh

@@ -247,5 +247,13 @@ EOF
 
 test_expect_success 'hierarchical section value' 'cmp .git/config expect'
 
+cat > .git/config << EOF
+[novalue]
+	variable
+EOF
+
+test_expect_success 'get variable with no value' \
+	'git-repo-config --get novalue.variable ^$'
+
 test_done