Fix conda installer selection in travis build script for Stackless build.

.travis.yml

@@ -74,15 +74,16 @@ matrix:
       language: cpp
       compiler: clang
       cache: false
-    - env: STACKLESS=true BACKEND=c
+    - env: STACKLESS=true BACKEND=c PY=2
       python: 2.7
-    - env: STACKLESS=true BACKEND=c
+    - env: STACKLESS=true BACKEND=c PY=3
       python: 3.6
   allow_failures:
     - python: pypy
     - python: pypy3
     - python: 3.8-dev
-    - env: STACKLESS=true BACKEND=c
+    - env: STACKLESS=true BACKEND=c PY=2
+    - env: STACKLESS=true BACKEND=c PY=3
   exclude:
     - python: pypy
       env: BACKEND=cpp
@@ -106,7 +107,8 @@ before_install:
 
   - |
     if [[ "$TRAVIS_OS_NAME" == "osx" -o "$STACKLESS" == "true" ]]; then # Install Miniconda
-      curl -s -o miniconda.sh https://repo.continuum.io/miniconda/Miniconda$PY-latest-MacOSX-x86_64.sh;
+      if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then CONDA_PLATFORM=MacOSX; else CONDA_PLATFORM=Linux; fi;
+      curl -s -o miniconda.sh https://repo.continuum.io/miniconda/Miniconda$PY-latest-${CONDA_PLATFORM}-x86_64.sh;
       bash miniconda.sh -b -p $HOME/miniconda && rm miniconda.sh;
       export PATH="$HOME/miniconda/bin:$PATH"; hash -r;
       #conda install --quiet --yes nomkl --file=test-requirements.txt --file=test-requirements-cpython.txt;