Merge branch 'jc/signed-commit' into next

* jc/signed-commit:
  pretty: %G[?GS] placeholders
  parse_signed_commit: really use the entire commit log message
  test "commit -S" and "log --show-signature"
  t7004: extract generic "GPG testing" bits
  log: --show-signature
  commit: teach --gpg-sign option
  Split GPG interface into its own helper library

Conflicts:
	builtin/merge.c
	t/lib-gpg.sh
	t/t7004-tag.sh

commit.h

@@ -183,6 +183,9 @@ struct commit_list *reduce_heads(struct commit_list *heads);
 
 extern int commit_tree(const char *msg, unsigned char *tree,
 		struct commit_list *parents, unsigned char *ret,
-		const char *author);
+		       const char *author, const char *sign_commit);
+
+extern int parse_signed_commit(const unsigned char *sha1,
+			       struct strbuf *message, struct strbuf *signature);
 
 #endif /* COMMIT_H */