context: re-add `overlayworkingctx._compact()` removed in 6a5dcd754842 This partially backs out 6a5dcd754842. The method was and is unused, but a call to it is introduced in the next patch. Differential Revision: https://phab.mercurial-scm.org/D8842

push: test for checks preventing publishing obsolete changeset The main difference from the previous test is how the changeset was obsoleted. In this case it is an amend so publishing the orphan would also create phase divergence. This must not go unnoticed.

push: test for checks preventing publishing obsolete changeset This introduce a simple example, more are coming. See inline documentation for details.

push: another test for checks preventing pushing orphaness to a server In this one, orphan was create with and amend instead of a prune.

push: test the checks preventing pushing orphaness to a server This is introduce a simple example, more are coming. See inline documentation for details.

exchange: backout changeset c26335fa4225 Changeset c26335fa4225 has good intends but introduce significant behavior regressions for multiple important cases. In short there are many case where push would have caught instability creation/propagation that are no longer covered. These behavior have been covered for many years and even if some related case are not currently caught, the covered one should not be regressed. The next four changesets introduce tests for some of these cases. However we could produce many more tests cases since the area is wide and they are many possible combination. (And we should cover them when getting back to this issue) Since 5.5 is one week away, the most reasonable approach seems to back this out while we devise a new way to move forward that preserve the current behavior, catch more issues and also improves the situation that c26335fa4225 target. In addition to the behavior change, c26335fa4225 also introduced output changes. These output changes does not requires a backout per-se, but are part of the same changeset. However they come with a couple of issues that also requires attention: 1) the bulk of the error message have been shoehorned into a multiple line abort message. This seems quite different from what we usually do. The abort message should be a compact and efficient message, with extra details being issued as normal error output beforehand. (with --verbose/--quiet) support. 2) the current output is unbounded, so if there is many (tens, hundreds, thousands, …) of unstable/obsolete changeset involved in the push, the output can quickly become a scary and un-usuable wall of text. So we need some limitation here (same as we have with the remote head list that says A, B , C and # others).

tests: glob 'mercurial.error' in test-phases.t On python 2 with chg, `mercurial.error` is omitted while printing error. On other cases it's there in error message. I did tried to understand what might be the cause was unable to find one on quick skim through the code.