Google Drive Converter Upload response header now spells "location" instead of "Location"

We encounter this issue on 4/23, when the google drive converter on our site decided to output blank document. 

After rounds of debug, I found out that when start_document_conversion method in files/converter/googledrive/classes/converter.php uploads the document to google drive, and reads the response header to look for the location of the document download link, it tries to match "Location". 

But somehow google is now responding with "location", causing the method can't find the download link and marks the conversion failed.

The solution for us is just change Line 127 of files/converter/googledrive/classes/converter.php so it match "location" instead of "Location". I guess one can also just match it lowercase to ensure it work both way. 

I am not certain if this is a one off case for our account.. it is strange for api to change response this way. But just want to point this out to help others with the same issue.