Test framework still generates .py files

[Matt Giuca]

It doesn't actually create Python files (that functionality has long been removed). But the test framework still runs marsc with -o and a random .py filename (in which it puts a .mas file).

Don't remove this functionality, as we may actually want to generate an output file in the future. Just change to use the same algorithm for generating a .mas file as Mars itself uses. Or better, put them in /tmp so we don't have to see them.

(Note: It usually deletes them so you don't see them. But if it fails badly it may not delete, and also it's still bad even if it does delete them.)

[Matt Giuca (mgiuca)]

Fixed in trunk r962.