Update _virtualenv.py

Signed-off-by: Bernat Gabor <bgabor8@bloomberg.net>

src/virtualenv/create/via_global_ref/_virtualenv.py

@@ -3,6 +3,7 @@
 
 import os
 import sys
+from copy import deepcopy
 
 VIRTUALENV_PATCH_FILE = os.path.join(__file__)
 
@@ -56,18 +57,26 @@ def find_spec(self, fullname, path, target=None):
                         spec = find_spec(fullname, path)
                         if spec is not None:
                             # https://www.python.org/dev/peps/pep-0451/#how-loading-will-work
-                            loader = spec.loader
+                            # https://www.python.org/dev/peps/pep-0451/#how-loading-will-work
+                            loader = deepcopy(spec.loader)  # loaders may be shared, create new that also patches
+                            spec.loader = loader
+                            if hasattr(loader, "exec_module"):  # new API
 
-                            def exec_module(module):
-                                old(module)
-                                patch_dist(module)
+                                def exec_module(module):
+                                    old(module)
+                                    patch_dist(module)
 
-                            if hasattr(loader, "exec_module"):
                                 old = loader.exec_module
                                 loader.exec_module = exec_module
-                            else:
+                            else:  # legacy API
+
+                                def load_module(name):
+                                    module = old(name)
+                                    patch_dist(module)
+                                    return module
+
                                 old = loader.load_module
-                                loader.load_module = exec_module
+                                loader.load_module = load_module
                             return spec
                     finally:
                         self.fullname = None