BLD: make 3.6 use *only* conda-forge channels

Author: jreback

.travis.yml

@@ -86,6 +86,7 @@ matrix:
         - JOB_NAME: "36"
         - TEST_ARGS="--skip-slow --skip-network"
         - PANDAS_TESTING_MODE="deprecate"
+        - CONDA_FORGE=true
       addons:
         apt:
           packages:

ci/install_travis.sh

@@ -53,12 +53,19 @@ conda config --set ssl_verify false || exit 1
 conda config --set always_yes true --set changeps1 false || exit 1
 conda update -q conda
 
-# add the pandas channel to take priority
-# to add extra packages
 echo "[add channels]"
-conda config --add channels pandas || exit 1
-conda config --remove channels defaults || exit 1
-conda config --add channels defaults || exit 1
+if [ "$CONDA_FORGE" ]; then
+    # use only the conda-forge channels
+    conda config --add channels pandas || exit 1
+    conda config --remove channels defaults || exit 1
+    conda config --add channels conda-forge || exit 1
+else
+    # add the pandas channel to take priority
+    # to add extra packages
+    conda config --add channels pandas || exit 1
+    conda config --remove channels defaults || exit 1
+    conda config --add channels defaults || exit 1
+fi
 
 conda install anaconda-client