Support jj 0.37+ detailed conflict marker format

[nertzy]

Since jj 0.37.0, conflict markers include detailed labels with change IDs, commit hashes, and descriptions instead of the previous generic side #N labels. The start/end markers also changed from uppercase Conflict to lowercase conflict. Since jj 0.25.0, markers may be longer than 7 characters.

Before (jj < 0.37):

<<<<<<< Conflict 1 of 1
%%%%%%% Changes from base to side #1
+++++++ Contents of side #2
>>>>>>> Conflict 1 of 1 ends

After (jj 0.37+):

<<<<<<< conflict 1 of 1
%%%%%%% diff from: rlvkpnrz 2f040964 (rebased revision's parent)
\\\\\\\        to: rlvkpnrz d44febc2 (rebase destination)
+++++++ zsuskuln f7705e4f (rebased revision)
>>>>>>> conflict 1 of 1 ends

Changes:

• Case-insensitive start/end markers (conflict vs Conflict)
• Accept any label text on %%%%%%% and +++++++ lines (not just Changes from... / Contents of...)
• Skip \\\\\\\ continuation lines used for multi-line conflict labels
• Support markers longer than 7 characters (e.g. <<<<<<<< for files already containing 7-char marker-like lines)

Test coverage: New test_diff_two_sides_detailed snapshot test with realistic jj 0.37+ conflict output, plus expanded regex pattern tests covering classic, detailed, and extended-length formats.

Relevant jj changelog entries:

• 0.37.0: "Conflict labels now contain information about where the sides of a conflict came from"; "\\\\\\\ markers to indicate the continuation of a conflict label"
• 0.25.0: "Conflict markers are now allowed to be longer than 7 characters"

[nilskch]

Thanks for working on this! I just installed jj 0.38.0 and created a simple conflict:

<<<<<<< conflict 1 of 1
%%%%%%% diff from: mntrysmr 14bb871e "Support jj 0.37+ detailed conflict marker format" (parents of rebased revision)
\\\\\\\        to: lrnzuvum fd58b68f (rebase destination)
+a
+b
+c
+d
+e
+++++++ otsmsqqu e0611812 (rebased revision)
1
2
3
4
5
6
>>>>>>> conflict 1 of 1 ends

I compiled this branch and the LSP could not find the conflict. Can you take a look at this?

[nertzy]

@nilskch updated to better support your use case where the conflict is at the beginning of the file (there was an existing bug where the first line was not being tested).

[nilskch]

Thank you and awesome catch :)

[nilskch]

I've sent you an invitation to become a collaborator. Feel free to just merge things like this in the future. I now work in a much smaller team and rarely have conflicts anymore, so I didn't notice that the conflict markers changed in recent jj versions.