setup: remove unused py_modules argument to setup() It is never populated and is useless clutter.

test-merge-changedelete.t: add resolve --list output We're going to move change/delete conflicts to the resolve phase, and the resolve --list output is one of the things that will be important to test.

test-merge-changedelete.t: add a file with regular merge conflicts In upcoming patches we're going to move change/delete conflicts to the resolve phase -- it will be important to see how regular conflicts interact with change/delete ones.

filemerge: in ':prompt', use ':fail' tool rather than returning directly The ':fail' tool now knows to write out the changed side for change/delete conflicts. This has no impact right now but will make things better when we move change/delete conflicts in here.

filemerge: in ':fail' tool, write out other side if local side is deleted We do this because we don't want to modify the dirstate for failures, and don't just want to leave the file missing from disk. Plus it's more useful for the user if the changed side is written out -- it is easier to delete a file than to get it back via hg revert.

mergestate: explicitly forget 'dc' conflicts where the deleted side is picked Once we move change/delete conflicts into the resolve phase, a 'dc' file might first be resolved by picking the other side, then later be resolved by picking the local side. For this transition we want to make sure that the file goes back to not being in the dirstate. This has no impact on conflicts during the initial merge.