Disable doctests on Py3 (ordering and other minutiae are too non-deterministic)

.gitlab-ci.yml

 Python 2.7 AMD CPU:
   script:
-  - py_version=2.7
+  - export PY_EXE=python2.7
   - export PYOPENCL_TEST=amd:pu
-  - EXTRA_INSTALL="numpy mako"
+  - export EXTRA_INSTALL="numpy mako"
   - curl -L -O -k https://gitlab.tiker.net/inducer/ci-support/raw/master/build-and-test-py-project.sh
   - ". ./build-and-test-py-project.sh"
   tags:
@@ -12,9 +12,10 @@ Python 2.7 AMD CPU:
   - tags
 Python 3.4 AMD CPU:
   script:
-  - py_version=3.4
+  - export PY_EXE=python3.4
   - export PYOPENCL_TEST=amd:pu
-  - EXTRA_INSTALL="numpy mako"
+  - export EXTRA_INSTALL="numpy mako"
+  - export NO_DOCTESTS=1
   - curl -L -O -k https://gitlab.tiker.net/inducer/ci-support/raw/master/build-and-test-py-project.sh
   - ". ./build-and-test-py-project.sh"
   tags: