Fix prefix to be normalized. Apparently the python file dialog returns front-slashed filenames, even on windows.

src/calibre/devices/folder_device/driver.py

@@ -54,6 +54,7 @@ class FOLDER_DEVICE(USBMS):
     def __init__(self, path):
         if not os.path.isdir(path):
             raise IOError, 'Path is not a folder'
+        path = USBMS.normalize_path(path)
         if path.endswith(os.sep):
             self._main_prefix = path
         else:

src/calibre/devices/usbms/driver.py

@@ -90,7 +90,6 @@ class USBMS(CLI, Device):
                             #print 'update_metadata_item returned true'
                             changed = True
                     else:
-                        #print "adding new book", lpath
                         if bl.add_book(self.book_from_path(prefix, lpath),
                                               replace_metadata=False):
                             changed = True