tests/test-merge6

Fix hg push and hg push -r sometimes creating new heads without --force.
Fixing issue179.

The algorithm checks if there not more new heads on the remote side than heads
which become non-heads due to getting children.

Pushing this repo:
    m
   /\
3 3a|
|/  /
2 2a
|/
1

to a repo only having 1, 2 and 3 didn't abort requiring --force before.

Added test cases for this and some doc strings for used methods.

#!/bin/sh

cat <<'EOF' > merge
#!/bin/sh
echo merging for `basename $1`
EOF
chmod +x merge
HGMERGE=./merge; export HGMERGE

mkdir A1
cd A1
hg init
echo This is file foo1 > foo
echo This is file bar1 > bar
hg add foo bar
hg commit -m "commit text" -d "1000000 0"

cd ..
hg clone A1 B1

cd A1
rm bar
hg remove bar
hg commit -m "commit test" -d "1000000 0"

cd ../B1
echo This is file foo22 > foo
hg commit -m "commit test" -d "1000000 0"

cd ..
hg clone A1 A2
hg clone B1 B2

cd A1
hg pull ../B1
hg update -m
hg commit -m "commit test" -d "1000000 0"
echo bar should remain deleted.
hg manifest

cd ../B2
hg pull ../A2
hg update -m
hg commit -m "commit test" -d "1000000 0"
echo bar should remain deleted.
hg manifest