Revert pip cache changes. Use pip's built-in retry.

tools/travis_before_install.sh

@@ -49,7 +49,7 @@ fi
 virtualenv -p python ~/venv
 source ~/venv/bin/activate
 
-retry pip install -q wheel flake8 coveralls nose
+pip install --retries 3 -q wheel flake8 coveralls nose
 
 # on Python 3.2, use matplotlib 1.3.1
 if [[ $TRAVIS_PYTHON_VERSION == 3.2 ]]; then
@@ -60,9 +60,9 @@ fi
 for requirement in $WHEELBINARIES; do
     WHEELS="$WHEELS $(grep $requirement requirements.txt)"
 done
-retry pip install -q $WHEELHOUSE $WHEELS
+pip install --retries 3 -q $WHEELHOUSE $WHEELS
 
-retry pip install -q -r requirements.txt
+pip install --retries 3 -q -r requirements.txt
 
 
 section () {

tools/travis_notes.txt

@@ -14,8 +14,9 @@ the yaml file is valid.
      set -ex
    ```
 
-- Use the `retry` bash function from `before_install.sh` before a command to have it try 3 times before
-failing (useful for installing from third party sources).
+- Use the `retry` bash function from `before_install.sh` before a command to
+have it try 3 times before failing.
+- Use `pip install --retries N` for retrying package downloads.
 - Use the `section` function to start a folded section of the script.
 Section names must have underscores or dots instead of spaces and must be
 accompanied by a corresponding `section_end` call.

tools/travis_script.sh

@@ -44,7 +44,7 @@ else
 fi
 
 if [[ $PY == 2.* ]]; then
-    retry pip install -q pyamg
+    pip install --retries 3 -q pyamg
 fi
 
 section_end "Install.optional.dependencies"