commit walkers: setup_ident() to record correct committer in ref-log.

The function pull() in fetch.c calls write_ref_sha1(), which may
need committer identity to update the ref-log, so they need to
call setup_ident() before calling git_config() function.

Acked-by: Shawn Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

http-fetch.c

@@ -1226,6 +1226,7 @@ int main(int argc, const char **argv)
 	int arg = 1;
 	int rc = 0;
 
+	setup_ident();
 	setup_git_directory();
 	git_config(git_default_config);