Travis CI: Bring branch/tag management from rabbitmq-shovel

Author: dumbbell

.travis.yml

@@ -13,11 +13,18 @@ otp_release:
   - "18.0"
   - "19.0"
 
-# The checkout made by Travis is a "detached HEAD". We switch back
-# to a tag or a branch. This pleases our git_rmq fetch method in
-# rabbitmq-components.mk and the proper tag/branch is selected in
-# dependencies too.
-before_script: (test "$TRAVIS_TAG" && git checkout "$TRAVIS_TAG") || (test "$TRAVIS_BRANCH" && git checkout "$TRAVIS_BRANCH")
+# The checkout made by Travis is a "detached HEAD" and branches
+# information is missing. Our Erlang.mk's git_rmq fetch method relies on
+# it, so we need to restore it.
+#
+# We simply fetch master and, if it exists, stable branches. A branch is
+# created, pointing to the detached HEAD.
+before_script:
+  - |
+    git checkout -B "${TRAVIS_TAG:-${TRAVIS_BRANCH}}"
+    git remote add upstream https://github.com/$TRAVIS_REPO_SLUG.git
+    git fetch upstream stable:stable || :
+    git fetch upstream master:master || :
 
 script: make tests