Attempt to resolve issues on Windows

Author: shreve

nbgrader/coursedir.py

@@ -439,14 +439,16 @@ def find_notebooks(
         }
 
         # Convert to a Path and back to a string to remove any instances of `/.`
-        pattern = str(Path(pattern.replace(".", r"\.").format(**pattern_args)))
+        pattern = str(Path(pattern))
 
         if sys.platform == 'win32':
-            # Escape backslashes on Windows
+            # Escape backslashes on Windows before doing any other escaping
             pattern = pattern.replace('\\', r'\\')
 
+        pattern = pattern.replace(".", r"\.").format(**pattern_args)
+
         for file in files:
-            match = re.match(pattern, str(file.relative_to(self.root)))
+            match = re.match(pattern, str(file))
             if match:
                 results.append({ **kwargs, **match.groupdict(), "path": file })