BF: add more robust travis installs

Try a few times to install travis wheels before giving up.

.travis.yml

@@ -27,12 +27,13 @@ matrix:
       env:
         - DEPENDS="cython numpy scipy matplotlib h5py nibabel cvxopt scikit_learn"
 before_install:
+    - source tools/travis_tools.sh
     - virtualenv --python=python venv
     - source venv/bin/activate
     - python --version # just to check
-    - pip install nose # always
+    - retry pip install nose # always
     - sudo apt-get install libblas-dev liblapack-dev libatlas3gf-base
-    - pip install --timeout=60 --no-index -f http://travis-wheels.scikit-image.org $DEPENDS
+    - wheelhouse_pip_install $DEPENDS
     - if [ "${COVERAGE}" == "1" ]; then
       pip install coverage;
       pip install coveralls;

tools/travis_tools.sh

@@ -0,0 +1,25 @@
+# Tools for working with travis-ci
+export WHEELHOUSE="http://travis-wheels.scikit-image.org/"
+
+retry () {
+    # https://gist.github.com/fungusakafungus/1026804
+    local retry_max=5
+    local count=$retry_max
+    while [ $count -gt 0 ]; do
+        "$@" && break
+        count=$(($count - 1))
+        sleep 1
+    done
+
+    [ $count -eq 0 ] && {
+        echo "Retry failed [$retry_max]: $@" >&2
+        return 1
+    }
+    return 0
+}
+
+
+wheelhouse_pip_install() {
+    # Install pip requirements via travis wheelhouse
+    retry pip install --no-index --find-links $WHEELHOUSE $@
+}