Add architecture ppc64le to travis build

[ddeka2910]

Add support for architecture ppc64le.

Exclude python "pypy3.5" and "2.7" for ppc64le

This is part of the Ubuntu distribution for ppc64le. This helps us simplify testing later when distributions are re-building and re-releasing. For more info tag @gerrith3

[coveralls]

Coverage remained the same at 89.592% when pulling 40c0c50 on ddeka2910:master into 0a6aff7 on rubik:master.

[coveralls]

Coverage remained the same at 89.592% when pulling 40c0c50 on ddeka2910:master into 0a6aff7 on rubik:master.

[rubik]

Hi Debabrata, can you explain the reason of these additions? I am not familiar with those.

[ddeka2910]

@rubik We are trying to bring ppc64le (power pc little endian) architecture testing up to the point of Intel testing.

[gerrith3]

@rubik ppc64le is the architecture name for IBM's Power architecture based hardware. It is basically a computing platform like any Intel platform but with a different architecture set. Pretty much anything in open source can port to ppc64le and run - these platforms though are used more often for big banks and enterprises rather than dektop users (although there are some of the latter). Our goal has been to get end user parity between the Power servers and Intel servers, including catching any regressions in open source projects at top of tree by using the same testing infrastructure (CI) as is uses on Intel. Hopefully that provides some context.

[rubik]

@gerrith3 Thanks for the details Gerrit. I understand the reasons, but it looks to me that those tests should be done in a centralized repository outside of the specific repositories. This change makes each test build much longer and if something breaks on ppc64le the build will fail. The same tests can be run independently and outside of the repository.

[gerrith3]

@rubik By a centralized repository, are you suggesting we clone all github projects and run a test environment somewhere else on all of them? That's the scope of the problem that we are working on right now. The additional testing time is worth looking at, but how much more is it? It looks like your total test time for all configurations right now is under 5 minutes, not sure how that makes the additional effort here to be "too much"? We routinely test projects on Power that take 30-60 minutes and even a few with a couple of hours. Anything beyond that is split into smaller chunks usually, but I don't see a 5 minute build time difference as a real issue?