Store empty (default) branch in branch cache, too.
Operations on this branch don't work otherwise.
Reading branches.cache had to be adjusted to allow an empty label.
Adjusted reading of the cache tip for symmetry, no functional change here.
#!/bin/sh
# http://www.selenic.com/mercurial/bts/issue322
echo % file replaced with directory
hg init a
cd a
echo a > a
hg commit -Ama
rm a
mkdir a
echo a > a/a
echo % should fail - would corrupt dirstate
hg add a/a
cd ..
echo % directory replaced with file
hg init c
cd c
mkdir a
echo a > a/a
hg commit -Ama
rm -r a
echo a > a
echo % should fail - would corrupt dirstate
hg add a
cd ..
echo % directory replaced with file
hg init d
cd d
mkdir b
mkdir b/c
echo a > b/c/d
hg commit -Ama
rm -r b
echo a > b
echo % should fail - would corrupt dirstate
hg add b
exit 0