Support pip 10 in pip-diff

.idea/heroku-buildpack-python.iml

+<?xml version="1.0" encoding="UTF-8"?>
+<module type="PYTHON_MODULE" version="4">
+  <component name="NewModuleRootManager">
+    <content url="file://$MODULE_DIR$" />
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+  </component>
+  <component name="TestRunnerService">
+    <option name="PROJECT_TEST_RUNNER" value="Unittests" />
+  </component>
+</module>
\ No newline at end of file

.idea/misc.xml

+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="ProjectRootManager" version="2" project-jdk-name="Python 3.4.0 (~/miniconda2/envs/py34-monitor/bin/python)" project-jdk-type="Python SDK" />
+</project>
\ No newline at end of file

.idea/modules.xml

+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="ProjectModuleManager">
+    <modules>
+      <module fileurl="file://$PROJECT_DIR$/.idea/heroku-buildpack-python.iml" filepath="$PROJECT_DIR$/.idea/heroku-buildpack-python.iml" />
+    </modules>
+  </component>
+</project>
\ No newline at end of file

.idea/vcs.xml

+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="VcsDirectoryMappings">
+    <mapping directory="$PROJECT_DIR$" vcs="Git" />
+  </component>
+</project>
\ No newline at end of file

.vscode/settings.json

+{
+    "python.pythonPath": "/home/liujunxiao/.local/share/virtualenvs/django-boilerplate-98fJI8Wm/bin/python"
+}
\ No newline at end of file

bin/steps/pipenv

@@ -44,7 +44,7 @@ if [ ! "$SKIP_PIPENV_INSTALL" ]; then
         export PIPENV_VERSION="2018.5.18"
 
         # Install pipenv.
-        /app/.heroku/python/bin/pip install pipenv==$PIPENV_VERSION --upgrade --upgrade-strategy only-if-needed &> /dev/null
+        /app/.heroku/python/bin/pip install pipenv==$PIPENV_VERSION --upgrade &> /dev/null
 
         # Install the dependencies.
         if [[ ! -f Pipfile.lock ]]; then

vendor/pip-pop/pip-diff

@@ -12,9 +12,12 @@ Options:
 """
 import os
 from docopt import docopt
-from pip.req import parse_requirements
 from pip.index import PackageFinder
 from pip._vendor.requests import session
+try: # for pip >= 10
+    from pip._internal.req import parse_requirements
+except ImportError: # for pip <= 9.0.3
+    from pip.req import parse_requirements
 
 requests = session()