Use unsigned version format. This way can use one additional bit, and when encountering invalid revlogs with the first bit set don't produce python warnings or strange error messages.

#!/bin/sh

echo "[extensions]" >> $HGRCPATH
echo "mq=" >> $HGRCPATH

hg init a
cd a
hg qnew first.patch
hg qnew first.patch

touch ../first.patch
hg qimport ../first.patch

exit 0