config: propagate errors from get_backend_for_use

Now that get_backend_for_use can return other error codes (by virtue
of key-name normalization), make sure to propagate the appropriate
error code when used.

Author: vermiculus

src/libgit2/config.c

@@ -650,9 +650,10 @@ static int get_backend_for_use(git_config_backend **out,
 int git_config_delete_entry(git_config *cfg, const char *name)
 {
 	git_config_backend *backend;
+	int error = 0;
 
-	if (get_backend_for_use(&backend, cfg, name, BACKEND_USE_DELETE) < 0)
-		return GIT_ENOTFOUND;
+	if ((error = get_backend_for_use(&backend, cfg, name, BACKEND_USE_DELETE)) < 0)
+		return error;
 
 	return backend->del(backend, name);
 }
@@ -684,8 +685,8 @@ int git_config_set_string(git_config *cfg, const char *name, const char *value)
 		return -1;
 	}
 
-	if (get_backend_for_use(&backend, cfg, name, BACKEND_USE_SET) < 0)
-		return GIT_ENOTFOUND;
+	if ((error = get_backend_for_use(&backend, cfg, name, BACKEND_USE_SET)) < 0)
+		return error;
 
 	error = backend->set(backend, name, value);
 
@@ -1125,19 +1126,21 @@ int git_config_multivar_iterator_new(git_config_iterator **out, const git_config
 int git_config_set_multivar(git_config *cfg, const char *name, const char *regexp, const char *value)
 {
 	git_config_backend *backend;
+	int error = 0;
 
-	if (get_backend_for_use(&backend, cfg, name, BACKEND_USE_SET) < 0)
-		return GIT_ENOTFOUND;
+	if ((error = get_backend_for_use(&backend, cfg, name, BACKEND_USE_SET)) < 0)
+		return error;
 
 	return backend->set_multivar(backend, name, regexp, value);
 }
 
 int git_config_delete_multivar(git_config *cfg, const char *name, const char *regexp)
 {
 	git_config_backend *backend;
+	int error = 0;
 
-	if (get_backend_for_use(&backend, cfg, name, BACKEND_USE_DELETE) < 0)
-		return GIT_ENOTFOUND;
+	if ((error = get_backend_for_use(&backend, cfg, name, BACKEND_USE_DELETE)) < 0)
+		return error;
 
 	return backend->del_multivar(backend, name, regexp);
 }