tests/test-586

children extension: Don't abort when looking at the null revision.

Since 62c56d8f368b revlog.children only returns real children,
so this is no longer a problem.

#!/bin/sh
# a test for issue586

hg init a
cd a
echo a > a
hg ci -Ama

hg init ../b
cd ../b
echo b > b
hg ci -Amb

hg pull -f ../a
hg merge
hg rm -f a
hg ci -Amc

hg st -A