Wikimedia Bugzilla is closed!

There are three different places where this message is used, and I think there
should be three different messages.

In the page title, it's a good idea that we say that this is a log, and that it
shows user's blocks.

In the combobox, the important thing is that you are choosing the user's blocks
one, you already know you are choosing a log.

In the user's contributions page, it is important to remark that you are going
to visit *this user's* block log.

In English, "Block log" probably fits all spaces nicely, but in Spanish, slight
changes in the phrase are needed in each case to make it sound completely right.