support --temp-basedir for staring a new instance

qutebrowser/qutebrowser.py

@@ -222,9 +222,13 @@ def _validate_untrusted_args(argv):
 
 def start_new_instance(args):
     """start a new instance."""
+    import tempfile
     from qutebrowser.utils import standarddir
     from qutebrowser.misc import ipcclient
 
+    if args.temp_basedir:
+        args.basedir = tempfile.mkdtemp(prefix='qutebrowser-basedir-')
+
     # In order to get socket path for starting a new instance
     standarddir.init(args)
     return ipcclient.send(args)