I had a similar experience at the company where I write my Diplomarbeit (thesis). My Ubuntu could not update libpcsclite1, because the proxy did not allow to fetch the package. Playing a bit with the URL a bit revealed that libpcsclite1 includes 'clit'. I had to fire up tor to get around that prude proxy.

[I was able to install Ubuntu in the first place, because I work at a department that does software development for rolling stock scheduling optimization. We are nearly the only ones in the company with computer that are not locked up.]

That's what happened here, it was even blocked as category: hacking. Only lasted about a week, though. Comforting in a way that they had a human check.

Happened at my work too, I emailed the person in charge of the filter to allow access, next day it was unblocked.