Problems with multiple remotes

[BatmanAoD]

I was trying to update a branch in my fork to resolve conflicts. After rebasing onto main@origin and resolving the conflict, I used jj git push, which...created a branch in martinvonz/jj rather than updating the remote from which I was tracking the branch.

As far as I know, jj branch doesn't have any way to delete a branch remotely without deleting it locally, or to specify only a particular remote on which to delete the branch. So I simply used git push --delete origin descendants-range.

But that caused jj to try to delete the branch anyway (note that the branch name is not present in the status output):

$> jj branch track descendants-range@personal
Done importing changes from the underlying Git repo.
Warning: Remote branch already tracked: descendants-range@personal
Nothing changed.
$> jj status
The working copy is clean
Working copy : prqmxzzk 9d9d8057 (empty) (no description set)
Parent commit: zswoqyzt 66989667 give descendants a range arg
$> jj branch set descendants-range -r @-
Error: No such branch: descendants-range
Hint: Use `jj branch create` to create it.
$> jj branch list
descendants-range (deleted)
  @personal: zswoqyzt hidden 3c1a7c7a give descendants a range arg
main: svposxsm e3bb825a jj git push: remove the NotFastForward error
Hint: Branches marked as deleted will be *deleted permanently* on the remote on the next `jj git push`. Use `jj branch forget` to prevent this.

This feels similar to #2504 in that it's a surprising (to me) change to the jj state that is automatically and unavoidably applied based on a change in the git state. But in this case, I'm frankly kind of baffled by the behavior:

• The branch was created via jj git branch track <name>@personal. Why did jj git push decide to push to origin rather than personal? I rebased onto main@origin rather than tracking main@origin and rebasing onto (local) main, but I don't see why that would affect which remote is used for tracking.
• git push --delete does not delete the local branch. So why did importing the git changes delete the local jj branch?
• ...once the jj branch was deleted, it was...very hard to recover. I understand why branch track is a no-op when the branch is marked for deletion (though the warning message should probably mention that), but there doesn't seem to be any good way to un-mark a branch for deletion. jj git fetch simply gave me Nothing changed (which seems weird because I actually started with personal as the only remote and added origin later, so the fetch default must be based on the name origin itself?), so I had to explicitly do jj branch forget descendants-range; jj git fetch --remote personal; jj branch track descendants-range@personal.

[BatmanAoD]

...come to think of it, I don't actually see how to update the main branch in my personal remote:

$> jj git push -b main --remote personal
Error: Non-tracking remote branch main@personal exists
Hint: Run `jj branch track main@personal` to import the remote branch.

Well, of course I don't want to track main@personal, I want to move it!

[yuja]

• The branch was created via jj git branch track <name>@personal. Why did jj git push decide to push to origin rather than personal? I rebased onto main@origin rather than tracking main@origin and rebasing onto (local) main, but I don't see why that would affect which remote is used for tracking.

Unlike Git, jj's local branch has doesn't have a notion of single upstream remote. The remote to push is purely selected by jj git push arguments (or config option.)

#1278

• git push --delete does not delete the local branch. So why did importing the git changes delete the local jj branch?

git push --delete basically created state after pulling deleted branch from remote, and the deleted remote branch was then imported because it was still tracked.

• ...once the jj branch was deleted, it was...very hard to recover. I understand why branch track is a no-op when the branch is marked for deletion (though the warning message should probably mention that), but there doesn't seem to be any good way to un-mark a branch for deletion. jj git fetch simply gave me Nothing changed (which seems weird because I actually started with personal as the only remote and added origin later, so the fetch default must be based on the name origin itself?), so I had to explicitly do jj branch forget descendants-range; jj git fetch --remote personal; jj branch track descendants-range@personal.

I think you can use jj branch create to revive the local branch.
Another easier option is to jj branch forget and re-fetch remote branches from all remotes.

[BatmanAoD]

Ah, I hadn't yet seen that the fetch and push remotes are configurable; that makes this easier. And yes, #1278 looks like it should solve the issue overall.

git push --delete basically created state after pulling deleted branch from remote, and the deleted remote branch was then imported because it was still tracked.

I guess that makes sense -- it's as if the remote branch were deleted and I did a fetch.

I think you can use jj branch create to revive the local branch.

Will jj branch create automatically track the branch? Or is this a special case where the "deleted" branch is already tracked, so branch create will just "adopt" the tracking info?

Another easier option is to jj branch forget and re-fetch remote branches from all remotes.

That's effectively what I ended up needing to do.

[yuja]

Will jj branch create automatically track the branch? Or is this a special case where the "deleted" branch is already tracked, so branch create will just "adopt" the tracking info?

jj branch create will keep the existing tracking state, but it seems a bit odd from UX. A deleted branch is still listed as "(deleted)", so it's not completely new to the user. It might be better to allow jj branch set instead.

Implementation-wise, tracking state is a property of remote branch, not local branch, and jj branch delete/set/create only touches local branch state.