Tests failing with run-tests.py SyntaxError

[Sean Owen]

  File "./dev/run-tests.py", line 124
    {m: set(m.dependencies).intersection(modules_to_test) for m in
modules_to_test}, sort=True)
                                                            ^
SyntaxError: invalid syntax


It seems like tests are failing intermittently with this type of error,
which leads me to guess there's some difference in the Python interpreter
on one or more machines but not all (?)

Does the error suggest anything to anyone who knows Python better than I?

The line has been around for a year so I don't think it's the script per se.