[PATCH 06/11] fetch: avoid unnecessary work when there is no current branch

["Johannes Schindelin via GitGitGadget" <gitgitgadget@gmail.com>]

From: Johannes Schindelin <johannes.schindelin@gmx.de>

As pointed out by CodeQL, `branch_get()` may return `NULL`, in which
case `branch_has_merge_config()` would return early, but we can even
avoid enumerating the refs prefixes in that case, saving even more CPU
cycles.

Technically, we should enclose these two statements in an `if (branch)
{...}` block, but the indentation is already quite deep, therefore I
refrained from doing that.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 builtin/fetch.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/builtin/fetch.c b/builtin/fetch.c
index c1a1434c7096..40a0e8d24434 100644
--- a/builtin/fetch.c
+++ b/builtin/fetch.c
@@ -1728,7 +1728,7 @@ static int do_fetch(struct transport *transport,
 			if (transport->remote->follow_remote_head != FOLLOW_REMOTE_NEVER)
 				do_set_head = 1;
 		}
-		if (branch_has_merge_config(branch) &&
+		if (branch && branch_has_merge_config(branch) &&
 		    !strcmp(branch->remote_name, transport->remote->name)) {
 			int i;
 			for (i = 0; i < branch->merge_nr; i++) {
-- 
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