Cancel button on a glossary upload doesn't cancel

Description of problem:
If the user presses the Cancel button when uploading a glossary, the dialog closes but does not stop the process

Version-Release number of selected component (if applicable):
3.7

How reproducible:
Easy always

Steps to Reproduce:
1. Login as admin, go to Glossary, click ... -> Upload
2. Select an upload file, press Upload
3. Quickly press Cancel

Actual results:
"Glossary succesfully uploaded" notification

Expected results:
The process should stop, or the Cancel button should become unavailable

Additional info: