this prevents us from retrying forever, spamming the log with warning…

…s: replace the invalid data with an empty string

git-svn-id: https://xpra.org/svn/Xpra/trunk@20413 3bb7dfac-3a0b-4e04-842a-767bc560f471

src/xpra/clipboard/clipboard_base.py

@@ -920,6 +920,7 @@ def unpack(clipboard, selection_data, _user_data=None):
             log("unpack %s: %s", clipboard, type(selection_data))
             global sanitize_gtkselectiondata
             if selection_data and sanitize_gtkselectiondata(selection_data):
+                self._clipboard.set_text("", len=-1)
                 selection_data = None
             if selection_data is None:
                 cb(None, None, None)