The following line, in the __sqlrepr__() method of the
SQLJoinConditional class, seems to be wrong:
using_columns = ", ".join()
The code is called when the using_columns argument is used.
I suppose it should be:
using_columns = ", ".join(using_columns)
But I'm not sure, because I'm not an expert of
Note: I'm not sure this is not already fixed, because
svn access is down at the time.