[with patch, positive review] Make the doctest timeouts in Sage easily adjustable

[mabshoff]

This is a left over from #717. The fix here is to define some env variables that can be used to overwrite the default doctesting timeouts. Those are defined in sage-doctest right at the top:

# the default timeout for doctests: 6 minutes (in seconds)
TIMEOUT      = 20
# the timeout value for long doctests: 30 minutes (in seconds)
TIMEOUT_LONG = 30 * 60
# the timeout for doctests running under valgrind tools: unreasonably long
TIMEOUT_VALGRIND = 1024*1024

Canonical names would be IMHO:

SAGE_TIMEOUT
SAGE_TIMEOUT_LONG
SAGE_TIMEOUT_VALGRIND

Bonus points for running some performance counter once and then adjusting the timeout by some factor on slower machines.

Cheers,

Michael

[jhpalmieri]

Here's a patch; apply to the scripts repository.

(This doesn't earn the bonus points Michael referred to.)

[ncalexan]

Fine by me.