HSC-1355: "with this fix, we get much better fringe subtraction".
Support multi-mode fringe subtraction
Implement and test the new API
IsrTask calls removeFringe in FringeTask but the method does not exist
Should only read fringe data after checking the filter
API Change for IsrTask (Backwards-compatible)
Sorry, please hold on about the review. I didn't run Jenkins before asking for review, and Jenkins failed. I'll investigate.
Fixed the previous problem. Jenkins passed: https://ci.lsst.codes/job/stack-os-matrix/label=centos-7/5943//console
Looks good; thanks. My only comment is really tangential to the work you've done here: rather than simply labelling something a "placeholder implementation" in the code, if we know it needs to be replaced we should have a ticket for it. You didn't add the comment, but since you're touching that piece of code maybe you could take the opportunity to make sure such a ticket exists and is referred to in the comments.
Other than that, good to merge.
Thank you for your review! I don't think there is a ticket for expanding the fringe correction yet; I'll search and create one if none is found, and make notes in the code.
Created DM-4441 for multiple frame fringe subtraction, and added the ticket number to the comment in the code.
Merged to master.