Fix file-changed-to-dir and dir-to-file commits (issue660). Allow adding to dirstate files that clash with previously existing but marked for removal. Protect from reintroducing clashes by revert. This change doesn't address related issues with update. Current workaround is to do "clean" update by manually removing conflicting files/dirs from working directory.

#!/bin/sh
#

hg init t
cd t
echo 1 > foo
hg ci -Am m

cd ..
hg clone t tt
cd tt
echo 1.1 > foo
hg ci -Am m

cd ../t
echo 1.2 > foo
hg ci -Am m
echo % should fail
hg pull -u ../tt

cd ../tt
echo % should fail
hg pull -u ../t
HGMERGE=true hg merge
hg ci -mm

cd ../t
echo % should work
hg pull -u ../tt