patch.diffopts: break get function into if statements We're going to add another condition here, and with the current structure that becomes just too confusing.

mdiff.diffopts: add a new noprefix option By popular demand, we introduce an option to disable the 'a/' and 'b/' prefixes in diff output. This makes copying and pasting filenames from diff output easier. This option will be implemented and documented in upcoming patches. To ensure that existing scripts that parse output don't break, we will ensure that this prefix is disabled in plain mode. A straight 'hg export | hg import' without HGPLAIN=1 will still be broken though, but there's little that can be done about that.

mdiff.diffopts: add doc comment for nobinary

changelog: register changelog.i.a as a temporary file The file is registered to make sure the transaction is cleaned up in all cases.