1376043 - Be less strict about content check in case of backouts

Status: RESOLVED WONTFIX

(Developer Services :: Servo VCS Sync, enhancement)

Description

[Gregory Szorc [:gps]]

+++ This bug was initially created as a clone of Bug #1375966 +++

Currently, the overlay extension ensures that file content in the destination revision agrees with the source content. Either the content must match the last overlayed changeset or must match the first parent of the first changeset to overlay. This ensures that diffs in source match up to diffs in the destination.

The content check fails in the following scenario:

1. Autoland repo closed
2. Servo commits made upstream and linearized to Mercurial
3. Backout touching servo/ made on Autoland
4. Backout PR merged into upstream Servo, *after* queued-but-not-overlayed commits
5. Overlay fails because Servo backout isn't at front of the queue and files changed by backout in Autoland don't match source.

I know glob has thought about this more than me. But the solution that comes to my mind is that the process invoking the overlay service should tell the overlay command which source changesets are backouts. Overlay can then look at the files changed by these changesets and allow a content mismatch if and only if mismatched files are modified by backouts *and* there would be no file merges. There will be a temporary divergence in the full manifest of file content. But the diffs should still match between source and destination.

Comment 1

[:glob ✱]

the sync service is no longer running/needed.