tests/test-update-reverse

verify: fix "missing revlog!" errors for revlog format v0 and add test

With revlog format v0 the .d files are empty if the only revision stored is an
empty file. Since Mercurial can no longer create format v0 repositories, but
still use it, add a script which creates a repository with a single empty file.
This can be used in other tests if wanted.

#!/bin/sh

hg init
touch a
hg add a
hg commit -m "Added a" -d "1000000 0"

touch main
hg add main
hg commit -m "Added main" -d "1000000 0"
hg checkout 0

echo Main should be gone
ls

touch side1
hg add side1
hg commit -m "Added side1" -d "1000000 0"
touch side2
hg add side2
hg commit -m "Added side2" -d "1000000 0"

hg log

echo Should have two heads, side2 and main
hg heads

echo Should show "a side1 side2"
ls

hg update --debug -C 1
echo Should only show "a main"
ls