Skip all grib tests for Python 3.

[pp-mo]

this is now a placeholder: DO NOT MERGE
see : #1833 (comment)

This excludes the grib tests from the standard test run in Python 3.
This is needed because we decided not to support Grib under Python 3 for the present,
because of outstanding problems (see #1806).

TO TEST:
running python3 setup.py test will generate various grib-related errors, which this removes.
Unfortunately, all tests won't run successfully under Python 3, until various other outstanding problems are resolved (see list in #1782)

[QuLogic]

Looks good to me.

[rhattersley]

Why grib instead of gribapi?

[pp-mo]

@rhattersley Why grib instead of gribapi?

Good point -- I think I wasn't quite clear in my mind what it is that we have problems with in Python 3.
Fixed.

[pp-mo]

what it is that we have problems with in Python 3.

Following offline discussion with @marqh ..
It now seems we don't need this after all.

Rather than disable Iris grib usage in Python 3 (which only awaits a Python-3 functional gribapi), we have now instead removed the Python3 gribapi build from the scitools channel.

• conda-recipes-scitools #118
• specific commit

So there is then no need to treat this as a special case : When installed under Python3 you have no gribapi, so it automatically skips the tests.

[pp-mo]

it automatically skips the tests.

... except it isn't working, for me.
I think an iris.proxy solution may be getting in the way.
cf : #1838 "Deprecate iris.proxy"
So something may still be needed here : but this commit is not it
this is now a placeholder: DO NOT MERGE...

[QuLogic]

Are you sure it isn't working? I just ran all tests without gribapi installed on Python 3.4 without any failures, except the one example that requires gribapi and isn't automatically skipped.

[pp-mo]

Are you sure it isn't working?

I think the problem may be local to my installation:
my conda is refusing to "forget" the gribapi build for Python3 that it used to have

I expect you'll get #1842 "Enable Python 3" functioning any time soon.
If so, that renders this obsolete + I'll close it.

[pp-mo]

Dead, not needed now that #1842 has gone in.