bzr fast-import --import-marks

[Eli Zaretskii]

"bzr fast-export-from-git" produces, in addition to a .fi stream, also
a .marks file, but if I pass that file to "bzr fast-import" via the
"--import-marks" option, bzr crashes:

  ABORT: exception occurred processing commit :2
  bzr: ERROR: bzrlib.errors.NoSuchRevision: CHKInventoryRepository('file:///D:/gnu/bzr/foo/.bzr/repository/') has no revision ('9432121c2ddc629db098b8d194275e0f8a1ce270',)

This is triggered by the following line in the .marks file:

  :2 9432121c2ddc629db098b8d194275e0f8a1ce270

>From the error message, it sounds like bzr tries to process this as if
it were a commit?

Is this a bug in fastimport, a cockpit error on my part, or some
problem with the marks file itself?

And btw, what is this file used for in the resulting bzr repository?
That is, what is the purpose of the --import-marks option? what
information it adds to the repository?

TIA