Issue 10971: Make test_zipimport_support once again compatible with refleak hunting (reviewed by Georg Brandl)

[commit during RC with Brett's approval]

The absolute_import statement got moved to a new Python 2.5 and Newer section
as it was available since then. The division statement got moved to Common
Gotchas since it has been around for so long that any modern Python program can
use it.

happens when the end exits before the beginning.

in the limited ABI

prevent garbage collection! (fortunately)

would lead to a decref of a NULL.

Fixes issue #11110.

If tested as '__main__' instead 'decimal', the tracebacks would
abbreviate 'decimal.Inexact' as 'Inexact', breaking the doctests.

(Reviewed by Antoine.)