Merge branch 'jk/verify-sig-merge-into-void'

"git merge" and "git pull" that merges into an unborn branch used
to completely ignore "--verify-signatures", which has been
corrected.

* jk/verify-sig-merge-into-void:
  pull: handle --verify-signatures for unborn branch
  merge: handle --verify-signatures for unborn branch
  merge: extract verify_merge_signature() helper
diff --git a/commit.h b/commit.h
index 03ab195..9866453 100644
--- a/commit.h
+++ b/commit.h
@@ -340,6 +340,14 @@ void record_author_date(struct author_date_slab *author_date,
 			struct commit *commit);
 
 int compare_commits_by_author_date(const void *a_, const void *b_, void *unused);
+
+/*
+ * Verify a single commit with check_commit_signature() and die() if it is not
+ * a good signature. This isn't really suitable for general use, but is a
+ * helper to implement consistent logic for pull/merge --verify-signatures.
+ */
+void verify_merge_signature(struct commit *commit, int verbose);
+
 int compare_commits_by_commit_date(const void *a_, const void *b_, void *unused);
 int compare_commits_by_gen_then_commit_date(const void *a_, const void *b_, void *unused);