Three directories missing from PATH are:
ruby: $TRAVIS_BUILD_DIR/vendor/bundle/bin or $BUNDLE_BIN if set
(Related to BUNDLE_PATH disappears)
php: $TRAVIS_BUILD_DIR/vendor/bin
That is where composer puts bins by default.
node_js: $TRAVIS_BUILD_DIR/node_modules/.bin
Node adds ./node_modules/.bin to PATH , and that likely helps with multipackage builds, however it also means that binaries magically disappear whenever the build changes directory. IMO, the relative directory should be first, and the absolute directory immediately afterwards.