travis: attempt to fix automatic deployment to PyPI for tagged version

Signed-off-by: Graeme Watt <graeme.watt@durham.ac.uk>

.travis.yml

@@ -17,11 +17,12 @@ install:
 script:
   - export CURRENT_PATH=`pwd`
   - docker run -v $CURRENT_PATH:$CURRENT_PATH hepdata/hepdata-converter /bin/bash -c "cd  $CURRENT_PATH && coverage run -m unittest discover hepdata_converter/testsuite 'test_*'"
-  - docker run -v $CURRENT_PATH:$CURRENT_PATH hepdata/hepdata-converter /bin/bash -c "cd  $CURRENT_PATH && python setup.py install && hepdata-converter -v"
+  - docker run -v $CURRENT_PATH:$CURRENT_PATH hepdata/hepdata-converter /bin/bash -c "cd  $CURRENT_PATH && python setup.py install sdist && hepdata-converter -v"
 after_success:
   - coveralls
 
 deploy:
+  skip_cleanup: true
   provider: pypi
   user: hepdata
   password: