Infer a --repository argument from command arguments when reasonable.
In particular: if invoked without -R from a CWD not inside a repo, having been
passed one or more file paths as command arguments, where the nearest enclosing
repo of all of those paths is the same, quietly infer a -R option for that repo.
Otherwise abort with an error message as before.
#!/bin/sh
mkdir t
cd t
hg init
echo 1 > a
hg ci -qAm "first" -d "1000000 0"
hg cp a b
hg mv a c
echo 2 >> b
echo 2 >> c
hg ci -qAm "second" -d "1000000 0"
hg co -C 0
echo 0 > a
echo 1 >> a
hg ci -qAm "other" -d "1000000 0"
hg merge --debug
echo "-- b --"
cat b
echo "-- c --"
cat c