Fix bug #345. The last hit for a file might have been before the last window, so we can't clear copies. To reduce the load, we only store real copy entries instead of storing hashes for every revision.

#!/bin/sh

hg init a
echo a > a/a
hg --cwd a ci -A -m a
hg clone a b
echo b > b/b
hg --cwd b ci -A -m b
chmod 100 a/.hg
hg --cwd b push ../a
chmod 700 a/.hg