configitems: add a new config option to control new filenode functionality This series is adding functionality where we can force create a new filenode for some files on a merge-commit. This is meant to represent an explicit choice made by user and hence distingusing the file in the merged commit with the file in parent by creating a new filenode instead of using the parent one. This introduces a experimental config option under which this functionality will be hidden. A new testcase is added in tests/test-merge-criss-cross.t to test the new functionality while making the option does not break other scenarios. Differential Revision: https://phab.mercurial-scm.org/D9026

git: add test showing `hg commit -i` working on a git repo Shows `hg commit -i` working on a git repo via the `git` extension. Adds working directory changes to files `alpha` and `beta`, then selects only `alpha` changes and commits them. As of now this would fail for a filename that includes uppercase characters due to the lack of case folding support in the extension. Differential Revision: https://phab.mercurial-scm.org/D9081

merge: replace calls to hg.updaterepo() by merge.update() The former no longer buys us anything. Differential Revision: https://phab.mercurial-scm.org/D9067

merge: add a higher-level update() for the common `hg update` use case This is different from the `update()` function that I just made private. The new function is specifically for the normal `hg update` use case. It doesn't do a merge and it doesn't do a clean (forced) update. Differential Revision: https://phab.mercurial-scm.org/D9066