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
mkdir t
cd t
hg init
echo "added file1" > file1
echo "added file2" > file2
hg add file1 file2
hg commit -m "added file1 and file2" -d "1000000 0" -u user
echo "changed file1" >> file1
hg commit -m "changed file1" -d "1000000 0" -u user
hg -q log
hg id
hg update -C 0
hg id
echo "changed file1" >> file1
hg id
hg revert --all
hg diff
hg status
hg id
hg update
hg diff
hg status
hg id
hg update -C 0
echo "changed file1" >> file1
HGMERGE=merge hg update
hg diff
hg status
hg id
hg revert --all
hg diff
hg status
hg id
hg revert -r tip --all
hg diff
hg status
hg id
hg update -C
hg diff
hg status
hg id