Issue #9573: os.fork now works when triggered as a side effect of import (the wisdom of actually relying on this remains questionable!)

Patch by Xuanji Li.

Split a common setUp/tearDown into the appropriate parts.

much larger than operand `b`.  Patch by Andrew Bennetts.

Issue 9873: the URL parsing functions now accept ASCII encoded byte sequences in addition to character strings

Skip the test if encoding fails.