test clear cache and cache requirements.txt

bin/steps/pip-install

@@ -47,6 +47,8 @@ if [ ! "$SKIP_PIP_INSTALL" ]; then
     if [ ! -f "$BUILD_DIR/.heroku/python/bin/pip" ]; then
         exit 1
     fi
+
+
     /app/.heroku/python/bin/pip install -r "$BUILD_DIR/requirements.txt" --exists-action=w --src=/app/.heroku/src --disable-pip-version-check | tee "$WARNINGS_LOG" | cleanup | indent
     PIP_STATUS="${PIPESTATUS[0]}"
     set -e
@@ -60,6 +62,10 @@ if [ ! "$SKIP_PIP_INSTALL" ]; then
 
     # Cache pip packages ourselves
     ## TODO: Update to cache pip's built-in cache
+
+    # Update cached version of requirements.txt
+    cp -R $BUILD_DIR/requirements.txt "$CACHE_DIR/.heroku/requirements.txt"
+
     cp requirements.txt .heroku/python/requirements-declared.txt
     /app/.heroku/python/bin/pip freeze --disable-pip-version-check > .heroku/python/requirements-installed.txt
 

bin/steps/python

@@ -96,6 +96,15 @@ if [ -f .heroku/python-version ]; then
 fi
 
 
+
+echo "$(diff "$BUILD_DIR/requirements.txt" "$CACHE_DIR/.heroku/requirements.txt")"
+
+# Remove python dependencies
+if [[ ! -f "$CACHE_DIR/.heroku/requirements.txt" ]] || [[ diff "$BUILD_DIR/requirements.txt" "$CACHE_DIR/.heroku/requirements.txt" ]]; then
+    puts-step "Clearing cached dependencies"
+    rm -rf .heroku/python
+fi
+
 if [ ! "$SKIP_INSTALL" ]; then
     puts-step "Installing $PYTHON_VERSION"
 
@@ -129,7 +138,7 @@ if ! curl -s "${GETPIP_URL}" -o "$GETPIP_PY" &> /dev/null; then
     exit 1
 fi
 
-# If Pip isn't up to date:
+# If a new Python has been installed or Pip isn't up to date:
 if [ "$FRESH_PYTHON" ] || [[ ! $(pip --version) == *$PIP_UPDATE* ]]; then
 
   puts-step "Installing pip"