fix pipenv test (#219)

Author: savil

testdata/python/pipenv/plan.json

@@ -0,0 +1,28 @@
+{
+  "shell_init_hook": "echo \"Creating/Using virtual environment in testdata/python/pipenv/.venv\";\npython -m venv \"testdata/python/pipenv/.venv\";\nsource \"testdata/python/pipenv/.venv/bin/activate\";",
+  "dev_packages": [
+    "python310",
+    "pipenv",
+    "python3"
+  ],
+  "runtime_packages": [
+    "python310",
+    "pipenv",
+    "python3"
+  ],
+  "install_stage": {
+    "command": "python -m venv .venv && source .venv/bin/activate && pip install -r requirements.txt",
+    "input_files": [
+      "."
+    ]
+  },
+  "build_stage": {
+    "command": "source .venv/bin/activate && \\\npip install pex && \\\nPACKAGE_NAME=$(python setup.py --name |  tr '[:upper:]-' '[:lower:]_') && \\\npex . -o app.pex -m $PACKAGE_NAME -r requirements.txt"
+  },
+  "start_stage": {
+    "command": "python ./app.pex",
+    "input_files": [
+      "app.pex"
+    ]
+  }
+}