using --diff-options to exclude a file

[Jamie Wilkinson]

Hey,

I'm trying to generate a diff between two branches, but I want to exclude
.bzrignore from the diff because it's not relevant to upstream.

bzr diff --diff-options='-x .bzrignore' ../upstream ./
seems like the right thing to do, but this dies with the following error:

dawn% bzr diff --diff-options='-x .bzrignore' ../upstream ./
=== added file '.bzrignore'
diff: standard output: Bad file descriptor
bzr: ERROR: external diff failed with 2; command: ['diff', '--label',
u'.bzrignore\t1970-01-01 00:00:00 +0000', '/tmp/bzr-diff-old-8CUmJB',
'--label', u'.bzrignore\t2006-07-25 02:16:36 +0000',
'/tmp/bzr-diff-new-Wv8Nqa', '--binary', '-u', '-x', '.bzrignore']

Is this a bug or am I using --diff-options the wrong way?