mergestate.add: store absentfilectxes as nullhex This is the most natural way to represent these files. We also need to make sure we don't try to store these files in the merge store.

mergestate._resolve: handle change/delete conflicts We will represent a deleted file as 'nullhex' in the in-memory and on-disk merge states. We need to be able to create absentfilectxes in that case, and delete the file from disk rather than try to write it out.

filemerge: don't try to copy files known to be absent We set 'back' to None in this case, so we need to handle that as well.

hgweb: use absolute_import

hgweb: import wsgicgi at top level There should be no practical reason to delay the import of wsgicgi.

hgweb: import BaseHTTPServer as module at top level This will avoid future warning spotted by the import checker.

hgweb: do not import hgweb_mod.hgweb and .makebreadcrumb as symbol It will be enforced by the import checker.

filemerge: don't try using external tools on change/delete conflicts This is mostly for completeness' sake -- the current code shouldn't get to this point.

filemerge: don't attempt to premerge change/delete conflicts This is mostly for completeness' sake -- at the moment we don't support any tools for change/delete conflicts that would do a premerge.

filemerge._mergecheck: add check for change/delete conflicts Merge tools that perform an actual 3-way merge can't handle change/delete conflicts. This adds a check for that.