Merge branch 'cc/fast-import-export-signature-names'

Clean up the way how signature on commit objects are exported to
and imported from fast-import stream.

* cc/fast-import-export-signature-names:
  fast-(import|export): improve on commit signature output format

gpg-interface.c

@@ -144,6 +144,18 @@ static struct gpg_format *get_format_by_sig(const char *sig)
 	return NULL;
 }
 
+const char *get_signature_format(const char *buf)
+{
+	struct gpg_format *format = get_format_by_sig(buf);
+	return format ? format->name : "unknown";
+}
+
+int valid_signature_format(const char *format)
+{
+       return (!!get_format_by_name(format) ||
+	       !strcmp(format, "unknown"));
+}
+
 void signature_check_clear(struct signature_check *sigc)
 {
 	FREE_AND_NULL(sigc->payload);