Avoided unnecessary list operations and delattr() calls that result
in an exception being raised as it causes call frame reconstruction
which is very costly, especially so in a function that is called
millions of times.

The original intent in refs #20536 was to use the highest protocol.
Calling zlib.compress() with a compression level of -1 seems to
fall back to the default level of 6.

Thanks Fako Berkers for help with the patch.

This reverts commit 49eee842 as it caused
a regression with test mirrors.

mysqlclient 1.3.7 fixes the test failures caused by 1.3.6.

A @font-face declaration may contain a fragment that looks like a relative path,
e.g. @font-face { src: url('../fonts/font.svg#../path/like/fragment'); }
In this case, an incorrect path was passed to the storage backend, which raised
an error that caused collectstatic to crash.

Thanks Aymeric for the initial patch and Carl for review.

Bail early if the input is a string since that's the most common case.

Thanks Josh, Anssi, and Carl for reviews and advice.

Forwardport of 3ded51bc from stable/1.8.x

Thanks to Kevin Turner for the report and Tim for the review.

Removed the bit about not allowing assignment to variables
because simple_tag now allows this.