Fix build status badge

[mbarkhau]

I'm not sure why this is currently red, maybe it references the latest build from here: https://travis-ci.org/hylang/hy/builds.

The image url with the explicit branch is probably the better choice.

[Kodiologist]

Because we're currently running Travis for PRs only, rather than both PRs and pushes, the badge probably won't work in any case. If so, we should just remove it.

[mbarkhau]

Ahh, I see. So this badge is actually referring to a build that is a few months old?

https://secure.travis-ci.org/hylang/hy.png?branch=master

[Kodiologist]

I suspect so. But it might also be referring to the last commit that was tested before being pushed (currently https://travis-ci.org/hylang/hy/builds/435140822), which is a reasonable backup. I'm not sure how to tell.

[mbarkhau]

Maybe this is helpful? https://stackoverflow.com/questions/31882306/how-to-configure-travis-ci-to-build-pull-requests-merges-to-master-w-o-redunda?rq=1

If it were me, and if it's possible, I'd just let it do another build after the merge to master of any pull request.

[Kodiologist]

The reason I turned off push builds originally was because of a longstanding Travis bug where if you accidentally push a PR branch to origin instead of your own fork, then it gets another redundant build, and if you remove the branch, the new build line sticks around in a permanent failure state. But branches: {only: master} could fix that. It's worth trying.

[Kodiologist]

The badges in question are gone as of #1811.