Wait, I see you already have a test that tests 'recursive-exclude     dirname     patterns` with extra spaces.  It works because `rest` is already stripped (which would not be necessary if you used `.split(None, 1)` here), and because patterns handle leading whitespace in the next line (because of `.split()`, if we ignore the redundant `.strip()`).

So, no bug here, but I'd prefer `.split(None, 1)` with no `.strip()` on the line above, for conciseness.

Actually wait, if tabs are allowed, then there _is_ a bug here, which would be fixed by using `.split(None, 1)`.  (I don't know if tabs are allowed by distutils.  My gut feeling is "yes".)