extdiff: refactor logic to diff revs of versions of files Now that code for both cases, diffing patches or files is in separate function, it will be better to refactor them more and understand. Differential Revision: https://phab.mercurial-scm.org/D8687

extdiff: refactor logic which does diff of patches The current extdiff code is hard to understand on first look. Took me few hours to grasp the code. Before adding more things, decided to do some refactoring. Differential Revision: https://phab.mercurial-scm.org/D8686

absorb: make it explicit if empty changeset was created If the config rewrite.empty-successor=skip is set, a message "became empty and was dropped" is shown if the changeset became empty. If the config rewrite.empty-successor=keep is set, absorb may create changesets even if they became empty. It’s probably a good idea to make that explicit. Therefore the message is changed to be a combination of both: "became empty and became ...". Repeating the word "became" is not very elegant. This results from the fact that "became" was and is overloaded to indicate both the change from non-empty to empty and the successor relation. In the combinated message, both meanings are used in one sentence.