run tests from correct branch on travis

script/run-tests.fish

@@ -1,4 +1,10 @@
 #!/usr/bin/env fish
+
+# When running on CI, run tests from the correct branch
+if set -q TRAVIS_BRANCH
+  command git checkout $TRAVIS_BRANCH
+end
+
 set -l result 0
 for test in (find * -type f -print | grep "spec.fish")
   fish $test $argv