This should be "True" instead of "TRUE"

Let's say "RBTools commands may print helpful hints"

"be provided" suggests to me that one could specify a value. Perhaps say "Hints can also be disabled by passing ..."?

Setting the repository type and name each enable different optimizations, and for best results users should have both in their config file. We should probably have separate hints.
Also, FYI, when we're wrapping a conditional like this we prefer using parentheses instead of the continuation character:

if (self.options.repository_name is None and
    self.options.repository_type is None):

This was already mixed up, but can we alphabetize this by key while we're editing it? That'll make it easier to read.

Space at the end of the string after the .

These log messages don't make it entirely clear why the user should set these or what the consequences are of not doing so. How about something like:
RBTools is auto-detecting the repository type, which can be slow. Adding REPOSITORY_TYPE to your .reviewboardrc will speed up rbt commands. Set ENABLE_HINTS=False to suppress this message.
RBTools is attempting to discover the matching repository in the Review Board server. Adding REPOSITORY_NAME to your .reviewboardrc will speed up rbt commands. Set ENABLE_HINTS=False to suppress this message.

Looking at those, I'm reconsidering my suggesting to combine them into a single message, but maybe there's a good way to word a single message without it being too excessively long.