phabricator: avoid creating unstable children within the review stack The instability occurred when rebasing something that has already been submitted onto something that hasn't, and then resubmitting the stack. Or as the test shows, just resubmitting and including something earlier that wasn't previously submitted. There's a general case here where any children (not just the ones in the range of commits posted for review) should be re-stabilized. But handling the selected commits here will cause the `local:commit` node values that are tracked on Phabricator to be properly kept in sync. Differential Revision: https://phab.mercurial-scm.org/D8436

phabricator: add an option to fold several commits into one review (issue6244) Now that all of the pieces are in place, alter the user facing command to allow it. This is the default behavior when using `arc`, but I much prefer the 1:1 approach, and I'm tempted to mark this advanced to limit its abuse. I started out calling this `--no-stack` like the feature request suggested, but I found it less obvious (especially when writing the code), so I went with the `hg fold` analogue. This will populate the `Commits` tab in the web UI with the hash of each commit folded into the review. From experimentation, it seems to list them in the order they are received from the extension instead of the actual parent/child relationship. The extension sends them in sorted order, thanks to `templatefilters.json()`. Since there's enough info there for them to put things in the right order, JSON is unordered aside from lists (IIUC), and there doesn't seem to be any harmful side effects, I guess we write this off as their bug. It is simple enough to workaround by putting a check for `util.sortdict` into `templatefilters.json()`, and don't resort in that case. There are a handful of restrictions that are documented in the code, which somebody could probably fix if they're interested. Notably, this requires the (default) `--amend` option, because there's not an easy way to apply a local tag across several commits. This also doesn't do preflight checking to ensure that all previous commits that were part of a single review are selected when updating. That seems expensive. What happens is the excluded commit is dropped from the review, but it keeps the Differential Revision line in the commit message. Not everything can be edited, so it doesn't seem worth making the code even more complicated to handle this edge case. There are a couple of "obsolete feature not enabled but X markers found!" messages that appeared on Windows but not macOS. I have no idea what's going on here, but that's an unrelated issue, so I conditionalized those lines. Differential Revision: https://phab.mercurial-scm.org/D8314

tests: move the phabricator auth token to the global config file The next commit introduces a new repo to simplify its development. This value needs to be modified to record tests, so it doesn't make sense to have to do that twice. The callsign and URL are *not* moved because there are tests that fallback to the .arcconfig file when those aren't present. Differential Revision: https://phab.mercurial-scm.org/D8390

phabricator: add debug logging to show previous node values in `phabsend` This isn't real useful here, but was very useful showing how `phabsend --fold` handles commits created by `hg fold` and `hg split`. It introduces a new debug function and flag instead of using `ui.debug()`, because `--debug` prints out all of the API chatter. Differential Revision: https://phab.mercurial-scm.org/D8389

rust: update README with new information about the Re2 path Differential Revision: https://phab.mercurial-scm.org/D8452

rust: add option of static linking a local Re2 install Previously, only dynamically linking the system-wide install was possible. We force the user to provide one to prevent hard-to-track errors. Differential Revision: https://phab.mercurial-scm.org/D8451

templatekw: cache mergestate even if merge is not ongoing While playing with eBPF, I noticed .hg/merge/state{,2} files were tried to open() for each revision. That's not healthy. Let's cache the "inactive" state as well.

revset: remove explicit sort() from unstable() The instability should be dealt with by baseset.__init__(), and the returned smartset is ordered by 'subset &' anyway.

revset: implement a simple 'foo#generations' expression The result of this expression is equivalent to 'foo#g[:]': all reachable ancestors and descendants of a revset foo. While not very useful functionality on its own, its implementation can be tested and revset.relations dict can be easily used by extensions to add other non-subscript relations. Differential Revision: https://phab.mercurial-scm.org/D8394

revset: rename generationsrel() to generationssubrel() This highlights that this is an implementation of 'x#y[z]' relation subscript operator as opposed to 'x#y' relation operator. Differential Revision: https://phab.mercurial-scm.org/D8393