I definitely agree with Vadim here: it's fairly silly that the
contrib userlock code is GPL'd, when it consists only of a few dozen
lines of wrapper for the real functionality that's in the main backend.
The only thing this licensing setup can accomplish is to discourage
people from using the userlock code; what's the value of that?
Besides, anyone who actually wanted to use the userlock code would need
only to write their own wrapper functions to get around the GPL license.
regards, tom lane