DEV: avoid buggy conda-build 3.0.3.

conda-build 3.0.3 removes its test environment even when asked not to.

Solution: Use earlier version of conda-build.

Author: pavoljuhas

.travis.yml

@@ -62,6 +62,11 @@ before_install:
   - $NOMC || test -x ~/mc/bin/conda || bash ${MYMCBUNDLE} -b -f -p ~/mc
   - $NOMC || popd
   - $NOMC || source ~/mc/bin/activate root
+
+  # Avoid failure due to bad handling of --dirty in conda-build 3.0.3.
+  # see https://github.com/conda/conda-build/issues/2166.
+  - $NOMC || echo 'conda-build <3' | tee ~/mc/conda-meta/pinned
+
   - $NOMC || conda update --yes conda
   - $NOMC || conda install --yes conda-build jinja2
   - $NOMC || conda create --name=testenv --yes python=${MYPYTHON_VERSION} coverage