Cannot lock LockDir(chroot-73350096:///~didrocks/unity/dep-session-shorcuts/.bzr/branch/lock): Transport operation not possible: readonly transport

[Robert Bruce Park]

I'm seeing very strange results with 'bzr missing' printing an error in spite of the command actually working:

$ bzr missing --show-ids --directory lp:~didrocks/unity/dep-session-shorcuts lp:unity --theirs-only
bzr: ERROR: Cannot lock LockDir(chroot-73350096:///~didrocks/unity/dep-session-shorcuts/.bzr/branch/lock): Transport operation not possible: readonly transport
Other branch has no new revisions.

("no new revisions" is correct)

Even weirder is that this doesn't happen without --theirs-only:

$ bzr missing --show-ids --directory lp:~didrocks/unity/dep-session-shorcuts lp:unity
You have 1 extra revision:
------------------------------------------------------------
revno: 4068
revision-id: <email address hidden>
parent: <email address hidden>
committer: Didier Roche <email address hidden>
branch nick: unity
timestamp: Wed 2016-01-27 18:04:45 +0100
message:
  Depends on session-shortcuts, prodiving easy way to shutdown, reboot, logout from dash

For now I'm workarounding my code by only inspecting stderr for errors if stdout is actually empty, but this is a strange error indeed.