Travis: Limit branch builds to master (#295)

…not much use having them in PRs.

Author: sjakobi

.travis.yml

@@ -1,6 +1,6 @@
 # This Travis job script has been generated by a script via
 #
-#   haskell-ci '--benchmarks-jobs= >=7.10' '--installed=-containers' '--installed=-binary' 'unordered-containers.cabal'
+#   haskell-ci '--benchmarks-jobs= >=7.10' '--installed=-containers' '--installed=-binary' 'unordered-containers.cabal' '--branches=master'
 #
 # To regenerate the script (for example after adjusting tested-with) run
 #
@@ -17,6 +17,9 @@ dist: xenial
 git:
   # whether to recursively clone submodules
   submodules: false
+branches:
+  only:
+    - master
 cache:
   directories:
     - $HOME/.cabal/packages
@@ -155,5 +158,5 @@ script:
   - rm -f cabal.project.local
   - ${CABAL} v2-build $WITHCOMPILER --disable-tests --disable-benchmarks all
 
-# REGENDATA ("0.10.2",["--benchmarks-jobs= >=7.10","--installed=-containers","--installed=-binary","unordered-containers.cabal"])
+# REGENDATA ("0.10.2",["--benchmarks-jobs= >=7.10","--installed=-containers","--installed=-binary","unordered-containers.cabal","--branches=master"])
 # EOF