Merge remote-tracking branch 'qubesos/pr/5'

* qubesos/pr/5:
  qfile-unpacker: Avoid data loss by checking for child errors

Fixes QubesOS/qubes-issues#1355

qubes-rpc/qfile-unpacker.c

@@ -90,5 +90,8 @@ int main(int argc __attribute((__unused__)), char ** argv __attribute__((__unuse
 	}
 	if (umount2(".", MNT_DETACH) < 0)
 		gui_fatal("Cannot umount incoming directory");
-	return ret;
+	if (!WIFEXITED(ret)) {
+		gui_fatal("Child process exited abnormally");
+	}
+	return WEXITSTATUS(ret);
 }