jj handles renames of the remote trunk poorly

[tonyfinn]

Description

Steps to Reproduce the Problem

1. Create a git repo with a master branch
2. Push the git repo to a remote
3. Run jj git init --colocate in this copy
4. Run jj branch track master@origin in this copy
5. From a different checkout of the git repo (or a different device/user), rename the branch master to main, push the new main branch to the remote, delete master on the remote
6. Run jj git fetch on the first checkout
7. Attempt to switch to the new main branch with jj new main

Expected Behavior

Ideally: You're able to continue developing the on local repo with the new name for the trunk branch.

At a minimum: Warn the target that the trunk() alias refers to has been deleted and you need to update the trunk() alias.

Actual Behavior

Output from jj git fetch in step 6:

> jj git fetch
bookmark: main@origin   [updated] tracked
bookmark: master@origin [deleted] untracked

Most jj commands fail after this jj git fetch.

> jj new main
Config error: Invalid `revset-aliases.immutable_heads()`
Caused by: Revision "master@origin" doesn't exist

> jj log
Error: Revision "master@origin" doesn't exist

> jj log -r main@origin
Error: Failed to parse template: In alias "builtin_log_node"
Caused by:
1:  --> 1:1
  |
1 | builtin_log_node
  | ^--------------^
  |
  = In alias "builtin_log_node"
2:  --> 6:10
  |
6 |       if(immutable, "immutable"),
  |          ^-------^
  |
  = Failed to evaluate revset
3: Revision "master@origin" doesn't exist
Hint: Did you mean "main@origin"

> jj bookmark untrack master@origin
Error: No such remote bookmark: master@origin

It's not clear how to recover from this situation other than rm -R .jj && jj git init --colocate

Specifications

• Platform: NixOS
• Version: 0.22.0

[yuja]

You'll need to update trunk() saved in .jj/repo/config.toml, which was probably generated by jj git init --colocate.

I agree the error message isn't actionable.