merge: always use other, not remote, in user prompts Now that we store and display merge labels in user prompts (not just conflict markets), we should rely on labels to clarify the two sides of a merge operation (hg merge, hg update, hg rebase etc). "remote" is not a great name here, as it conflates "remote" as in "remote server" with "remote" as in "the side of the merge that's further away". In cases where you're merging the "wrong way" around, remote can even be the "local" commit that you're merging with something pulled from the remote server.

merge: use labels in prompts to the user Now that we persist the labels, we can consistently use the labels in prompts for the user without risk of confusion. This changes a huge amount of command output: This means that merge prompts like: no tool found to merge a keep (l)ocal, take (o)ther, or leave (u)nresolved? u and remote changed a which local deleted use (c)hanged version, leave (d)eleted, or leave (u)nresolved? c become: no tool found to merge a keep (l)ocal [working copy], take (o)ther [destination], or leave (u)nresolved? u and remote [source] changed a which local [dest] deleted use (c)hanged version, leave (d)eleted, or leave (u)nresolved? c where "working copy" and "destination" were supplied by the command that requested the merge as labels for conflict markers, and thus should be human-friendly.

journal: use the dirstate parentchange callbacks Instead of hacking into dirstate internals let's use the callbacks to be notified about wd parent change.

dirstate: add callback to notify extensions about wd parent change The journal extension had to touch the dirstate internals to be notified about wd parent change. To make that detection cleaner and reusable let's move it core. Now the extension can register to be notified about parent changes.

revpair: do not optimize tree to check for odd-range spec At cc3a30ff9490, we had to optimize a parsed tree to resolve x^:y ambiguity. Since we've moved the resolution of x^:y to parse(), we no longer have to call optimize(). Therefore, (x:y) can be taken as a single expression, not an odd range expression x:y.

revset: also parse x^: as (x^): Given x^:y is (x^):y, this seems sensible.

revset: resolve ambiguity of x^:y before alias expansion This is purely a parsing problem, which should be resolved before alias expansion.