Move commands.forget over to using new walk code.
With no names, it now recursively forgets everything, as is the default
behaviour of other commands. And prints the names of all files it
hasn't specifically been told to forget.
#!/bin/sh
set -x
hg init
echo a > a
hg add a
hg commit -m "1" -d "0 0"
hg status
cp a b
hg copy a b
hg status
hg --debug commit -m "2" -d "0 0"
hg history
hg log a
hexdump -C .hg/data/b.d
hg cat b > bsum
md5sum bsum
hg cat a > asum
md5sum asum
hg verify