Don't die if template path cannot be read (#2162)

Author: stuaxo

nbconvert/exporters/templateexporter.py

@@ -565,13 +565,19 @@ def _template_paths(self, prune=True, root_dirs=None):
         for template_name in template_names:
             for base_dir in self.extra_template_basedirs:
                 path = os.path.join(base_dir, template_name)
-                if not prune or os.path.exists(path):
-                    paths.append(path)
+                try:
+                    if not prune or os.path.exists(path):
+                        paths.append(path)
+                except PermissionError:
+                    pass
             for root_dir in root_dirs:
                 base_dir = os.path.join(root_dir, "nbconvert", "templates")
                 path = os.path.join(base_dir, template_name)
-                if not prune or os.path.exists(path):
-                    paths.append(path)
+                try:
+                    if not prune or os.path.exists(path):
+                        paths.append(path)
+                except PermissionError:
+                    pass
 
         for root_dir in root_dirs:
             # we include root_dir for when we want to be very explicit, e.g.