Canceling on "recommended mods" tab doesn't stop the progress bar

[DasSkelett]

First of all, I think I can fix this myself, I just wanted to inform there's a bug. I'll open a PR then.
If I need help, I let you know.

Background

CKAN Version:
v1.25.1
(Should be in regular 1.25 too)

Problem

What steps did you take in CKAN?
Choosed a mod (with recommends) to install and applied the changes, than cancelled on the "Choose recommended mods"-tab page.

What did you expect to happen?
the progress bar stops running and the status label says sth. like "User cancelled Installation process!".

What happened instead?
The progress bar (StatusProgress) in the lower right corner keeps cycling as well as the StatusLabel just says "Error!" which is a bit vague and also incorrect, as there is no real error, just a cancellation.

Screenshots: