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
cat <<'EOF' > merge
#!/bin/sh
echo merging for `basename $1`
EOF
chmod +x merge
mkdir t
cd t
hg init
echo This is file a1 > a
hg add a
hg commit -m "commit #0" -d "1000000 0"
echo This is file b1 > b
hg add b
hg commit -m "commit #1" -d "1000000 0"
hg update 0
echo This is file c1 > c
hg add c
hg commit -m "commit #2" -d "1000000 0"
echo This is file b1 > b
echo %% no merges expected
env HGMERGE=../merge hg merge 1
hg diff --nodates
hg status
cd ..; rm -r t
mkdir t
cd t
hg init
echo This is file a1 > a
hg add a
hg commit -m "commit #0" -d "1000000 0"
echo This is file b1 > b
hg add b
hg commit -m "commit #1" -d "1000000 0"
hg update 0
echo This is file c1 > c
hg add c
hg commit -m "commit #2" -d "1000000 0"
echo This is file b2 > b
echo %% merge should fail
env HGMERGE=../merge hg merge 1
echo %% merge of b expected
env HGMERGE=../merge hg merge -f 1
hg diff --nodates
hg status
cd ..; rm -r t
echo %%
mkdir t
cd t
hg init
echo This is file a1 > a
hg add a
hg commit -m "commit #0" -d "1000000 0"
echo This is file b1 > b
hg add b
hg commit -m "commit #1" -d "1000000 0"
echo This is file b22 > b
hg commit -m "commit #2" -d "1000000 0"
hg update 1
echo This is file c1 > c
hg add c
hg commit -m "commit #3" -d "1000000 0"
echo 'Contents of b should be "this is file b1"'
cat b
echo This is file b22 > b
echo %% merge fails
env HGMERGE=../merge hg merge 2
echo %% merge expected!
env HGMERGE=../merge hg merge -f 2
hg diff --nodates
hg status
cd ..; rm -r t
mkdir t
cd t
hg init
echo This is file a1 > a
hg add a
hg commit -m "commit #0" -d "1000000 0"
echo This is file b1 > b
hg add b
hg commit -m "commit #1" -d "1000000 0"
echo This is file b22 > b
hg commit -m "commit #2" -d "1000000 0"
hg update 1
echo This is file c1 > c
hg add c
hg commit -m "commit #3" -d "1000000 0"
echo This is file b33 > b
echo %% merge of b should fail
env HGMERGE=../merge hg merge 2
echo %% merge of b expected
env HGMERGE=../merge hg merge -f 2
hg diff --nodates
hg status