Merge pull request #3758 from docdeveloper/patch-2

Adds info on env variables

docs/advanced.rst

@@ -71,6 +71,11 @@ Luckily - pipenv will hash your Pipfile *before* expanding environment
 variables (and, helpfully, will substitute the environment variables again when
 you install from the lock file - so no need to commit any secrets! Woo!)
 
+If your credentials contain a special character, surround the references to the environment variables with quotation marks. For example, if your password contain a double quotation mark, surround the password variable with single quotation marks. Otherwise, you may get a `ValueError, "No closing quotation"` error while installing dependencies.
+
+    [[source]]
+    url = "https://$USERNAME:'${PASSWORD}'@mypypi.example.com/simple"
+
 
 ☤ Specifying Basically Anything
 -------------------------------