run label missing from `_from-orig_to-T1w_mode-image_xfm.txt`

[fliem]

Related to #185
Issue due to #188
I have two T1w runs per session, but using poldracklab/smriprep:0.6.0 the resulting xfm file lost the run label (hence, I only have one xfm per session: smriprep/sub-{subject}/ses-{session}/anat/sub-{subject}_ses-{session}_from-orig_to-T1w_mode-image_xfm.txt)

[effigies]

Good catch. I think all of our test cases have been 1 T1w per session.

Fixing this will fix incorrect derivatives while leaving working derivatives alone, so this can be done as a bug-fix.

[oesteban]

@fliem, would it be easy for you to test the new niworkflows branch? How do you usually run smriprep?

[fliem]

@oesteban I can confirm that this works as expected.