Test the 3.7 branch on Travis

[johnbillion]

The 3.7 branch doesn't have a .travis.yml file included, so it doesn't get tested on Travis (it gets sent but immediately errors).

This is the only active branch which is not tested on Travis.

[swissspidy]

I know this task doesn't directly fall into a specific milestone, but changing the milestone to 4.8 is clear about intent without affecting 4.7.4 planning and reports.

[desrosj]

Copies .travis.yml file from 3.8 branch.

[desrosj]

Test build: ​https://travis-ci.org/desrosj/develop.wordpress/builds/225849822

[netweb]

Thanks @desrosj, can you update the patch so that it merges the proposed changes from #40549 here also please

[johnbillion]

This may as well be considered blocked until #40463 is fixed, plus the same for 3.9 and 3.8 most likely. We'll get there, little by little.

[netweb]

This will need the changes from #41292 merged into the patch here to prevent Travis CI attempting to test PHP 5.2 on Ubuntu Trusty

[johnbillion]

This is unlikely to happen.

[SergeyBiryukov]

Fixed in [47343] / #49485.