In closing #15927, R. David Murray said "Although this is clearly a bug fix, it also represents a behavior change that could cause a working program to fail.  I have therefore only applied it to 3.4, but I'm open to arguments that it should be backported." 

David, I'll leave you to evaluate the argument presented.

Vaibhav: in the meanwhile, consider moving your pipeline to 3.x or patching your copy of the csv module.  You can put it in sitepackes as csv27.  Or if you are distributing code anyway, include your patched copy with it.