Merge branch 'jc/mailinfo-cleanup-fix' into maint

Corner case bugfix.

* jc/mailinfo-cleanup-fix:
  mailinfo: avoid segfault when can't open files

mailinfo.c

@@ -1167,9 +1167,11 @@ void clear_mailinfo(struct mailinfo *mi)
 	strbuf_release(&mi->inbody_header_accum);
 	free(mi->message_id);
 
+	if (mi->p_hdr_data)
 		for (i = 0; mi->p_hdr_data[i]; i++)
 			strbuf_release(mi->p_hdr_data[i]);
 	free(mi->p_hdr_data);
+	if (mi->s_hdr_data)
 		for (i = 0; mi->s_hdr_data[i]; i++)
 			strbuf_release(mi->s_hdr_data[i]);
 	free(mi->s_hdr_data);