Index: release/scripts/modules/bpy/path.py
===================================================================
--- release/scripts/modules/bpy/path.py	(révision 58446)
+++ release/scripts/modules/bpy/path.py	(copie de travail)
@@ -92,15 +92,22 @@
        when not set the current filename is used.
     :type start: string
     """
+    def _check_same_drive(path1, path2):
+        return os.path.splitdrive(path1)[0] == os.path.splitdrive(path2)[0]
+
     if isinstance(path, bytes):
         if not path.startswith(b"//"):
             if start is None:
                 start = _os.path.dirname(_getattr_bytes(_bpy.data, "filepath"))
+            if not _check_same_drive(path, start):
+                return path
             return b"//" + _os.path.relpath(path, start)
     else:
         if not path.startswith("//"):
             if start is None:
                 start = _os.path.dirname(_bpy.data.filepath)
+            if not _check_same_drive(path, start):
+                return path
             return "//" + _os.path.relpath(path, start)
 
     return path