add -f/--force to pull, incoming, outgoing, to work on unrelated repo.
before this, push would not push from e.g. "hg" repo to "kernel" repo
but other commands worked. this was bad idea, could merge unrelated
projects by accident. i did this tonight.
now, all commands still work with unrelated repo but need
--force/-f. abort is default. this is safer.
#!/bin/sh
hg init
echo This is file a1 > a
hg add a
hg commit -m "commit #0" -d "1000000 0"
touch b
hg add b
rm b
hg commit -A -m"comment #1" -d "1000000 0"