alias: test duplicated definition earlier This patch moves the old definition checking logic introduced by f4b7be3f8430 earlier. So that the test itself does not depend on `aliasdef`. The check is to avoid wrapping a same alias multiple times. It can be done by checking the config name and value (`definition` in code), without constructing a `cmdalias` instance. This makes the next patch easier to review. Differential Revision: https://phab.mercurial-scm.org/D804

uncommit: add a test for uncommit with uncommitondirtywdir config in merge Differential Revision: https://phab.mercurial-scm.org/D809

largefiles: force an on-disk merge Largefiles isn't a good candidate for in-memory merge (it uses a custom dirstate, matcher, and the files might not fit in memory) so have it always run an old-style merge. Differential Revision: https://phab.mercurial-scm.org/D683

merge: allow a custom working context to be passed to update This will allow anyone to enable the first in-menmory merge milestone by wrapping merge.update in an extension and creating an overlayworkingctx. Differential Revision: https://phab.mercurial-scm.org/D682

patchbomb: add test that shows --to and --cc override matching config item As far as I know this has always been true and is intentional (it's in line with many other behaviors), but it wasn't tested.

blackbox: move _openlogfile to a separate method This removes several `stat` syscalls for accessing `_bbvfs` and makes `ui` object cleaner. Differential Revision: https://phab.mercurial-scm.org/D769

blackbox: do not prevent 'chg init' from working Previously, blackbox always appends to blackbox.log and creates the directory for that file on demand. That could be an issue if: 1. chg starts from `$REPO` directory, so `ui._bbrepo` is set. 2. `rm -rf $REPO`. 3. `chg init $REPO`, blackbox writes something and `init` will fail because `$REPO` directory is non-empty. This patch fixes that by verifying whether vfs exists before re-using it. Differential Revision: https://phab.mercurial-scm.org/D768