Install numpy>=1.15 for py27

.travis.yml

@@ -2,24 +2,24 @@ language: python
 python:
   - "2.7"
   - "3.6"
+  - "3.7"
 env:
-  - SPHINX_VERSION=1.3
-  - SPHINX_VERSION=1.4
   - SPHINX_VERSION=1.5
   - SPHINX_VERSION=1.6
   - SPHINX_VERSION=1.7
-  # - SPHINX_VERSION=1.8  # Not yet available on defaults conda channel
+  - SPHINX_VERSION=1.8
   - SPHINX_VERSION=""
 matrix:
   exclude:
-  - python: "3.6"
-    env: SPHINX_VERSION=1.3
-  - python: "3.6"
-    env: SPHINX_VERSION=1.4
+    - python: "3.7"
+      env: SPHINX_VERSION=1.5
+    - python: "3.7"
+      env: SPHINX_VERSION=1.6
 install:
   # We do this conditionally because it saves us some downloading if the
   # version is the same.
   - if [[ "$TRAVIS_PYTHON_VERSION" == "2.7" ]]; then
+      NUMPY="numpy>=1.15";
       wget https://repo.continuum.io/miniconda/Miniconda2-latest-Linux-x86_64.sh -O miniconda.sh;
     else
       wget https://repo.continuum.io/miniconda/Miniconda3-latest-Linux-x86_64.sh -O miniconda.sh;
@@ -31,7 +31,7 @@ install:
   - conda update -q conda
   # Useful for debugging any issues with conda
   - conda info -a
-  - conda create -n test_env python=$TRAVIS_PYTHON_VERSION matplotlib pillow sphinx=$SPHINX_VERSION jupyter pandoc
+  - conda create -n test_env python=$TRAVIS_PYTHON_VERSION matplotlib pillow sphinx=$SPHINX_VERSION jupyter pandoc $NUMPY
   - source activate test_env
   - if [[ $SPHINX_VERSION == "" ]]; then
       conda uninstall --force sphinx;