Quotation_strip fix actually caused the script not to work

My sincerest apologies to anyone who's downloaded the script in the past
few *months* and received the error "coercing to Unicode: need string or
buffer, NoneType found" -- I somehow managed to commit my code without
noticing the script didn't work at all even on my own computer. (Which
is very strange, because I'm certain I tested it at some point. Who
knows.)

Anyway, this should solve the issue. (input_file was always receiving
None owing to the lack of a variable after return.)
Merge branch 'master' of https://github.com/sobjornstad/AnkiLPCG