merge: add more thorough tests for --force With generate-working-copy-states.py generalized to support arbitrarily many changesets, we can use it for generating test cases for merge: use one changeset each for base, remote and local. With the various working copy states, this is a total of 104 cases. The first candidate for additional testing is 'hg merge --force'. Even though the force option is deprecated, it is convenient for testing because it can be tested without first needing to revert any changes. Except for the lack of checking for uncommitted changes, it differs in only a few cases from unforced merge. The new tests cover all the cases in the existing test-merge-force.t, except for the unforced merge case, which is covered in several other files anyway, so nothing remains of the file after this patch.