Don't ignore errors in shell scripts
diff --git a/.travis-build-without-test.sh b/.travis-build-without-test.sh
index 16e24e9..2c84e9d 100755
--- a/.travis-build-without-test.sh
+++ b/.travis-build-without-test.sh
@@ -1,6 +1,9 @@
 #!/bin/bash
 ROOT=$TRAVIS_BUILD_DIR/..
 
+# Fail the whole script if any command fails
+set -e
+
 # jsr308-langtools
 (cd $ROOT && hg clone https://bitbucket.org/typetools/jsr308-langtools)
 (cd $ROOT/jsr308-langtools/ && ./.travis-build-without-test.sh)