Seems like branches with @ in the name are replicated across, however the branch name appears with @ as %40 in the mirrored org, which means it always thinks the branch doesn't exist when checking for it.
Suspect this is a problem with encoding on some github library calls but not others - the encoding was introduced because some branches were broken due to other characters which I now can't remember.
Syncing frontend...
Seems like branches with @ in the name are replicated across, however the branch name appears with @ as %40 in the mirrored org, which means it always thinks the branch doesn't exist when checking for it.
Suspect this is a problem with encoding on some github library calls but not others - the encoding was introduced because some branches were broken due to other characters which I now can't remember.