Merge branch 'jc/fix-clone-single-starting-at-a-tag' into maint

"git clone -b brefs/tags/bar" would have mistakenly thought we were
following a single tag, even though it was a name of the branch,
because it incorrectly used strstr().

* jc/fix-clone-single-starting-at-a-tag:
  builtin/clone.c: detect a clone starting at a tag correctly

Author: gitster

builtin/clone.c

@@ -695,7 +695,7 @@ static void write_refspec_config(const char* src_ref_prefix,
 	if (option_mirror || !option_bare) {
 		if (option_single_branch && !option_mirror) {
 			if (option_branch) {
-				if (strstr(our_head_points_at->name, "refs/tags/"))
+				if (starts_with(our_head_points_at->name, "refs/tags/"))
 					strbuf_addf(&value, "+%s:%s", our_head_points_at->name,
 						our_head_points_at->name);
 				else