Use os.path.lexists when checking for virtualenvs

CHANGES.txt

@@ -23,6 +23,9 @@
   distributions for interpreters other than the one pip is being run on.
   (:pull:`3760`)
 
+* Skip scanning virtual environments even when venv/bin/python is a dangling
+  symlink.
+
 
 **8.1.2 (2016-05-10)**
 

pip/req/req_install.py

@@ -483,7 +483,7 @@ class InstallRequirement(object):
                         # Don't search in anything that looks like a virtualenv
                         # environment
                         if (
-                                os.path.exists(
+                                os.path.lexists(
                                     os.path.join(root, dir, 'bin', 'python')
                                 ) or
                                 os.path.exists(