Trac ticket query should be case insensitive.

[Lachezar Dobrev]

The current implementation of the Trac ticket query system is case sensitive, which is very frustrating.

Searching for Owner=Jonas does not yield the same results as searching for Owner=jonas.

This makes it very hard to find your own tickets if your user name is not lowercase, and puts up a lot of problems finding whether there is already an entered ticket on a specific subject.

The fixes in [4435] and #4363 do not fix this issue.

[cboos]

Worksforme here on t.e.o, and in my local test environments (SQLite, MySQL and PostgreSQL), with 0.11-stable.

If someone can reproduce the issue, please reopen with detailed information about the setup.