Pass none for library_uuid when opening a device in contexts where no library is available

src/calibre/devices/__init__.py

@@ -30,7 +30,6 @@ def strftime(epoch, zone=time.gmtime):
 def get_connected_device():
     from calibre.customize.ui import device_plugins
     from calibre.devices.scanner import DeviceScanner
-    import uuid
     dev = None
     scanner = DeviceScanner()
     scanner.scan()
@@ -48,7 +47,7 @@ def get_connected_device():
 
     for d in connected_devices:
         try:
-            d.open(str(uuid.uuid4()))
+            d.open()
         except:
             continue
         else:

src/calibre/devices/prs500/cli/main.py

@@ -6,7 +6,7 @@ Provides a command-line and optional graphical interface to the SONY Reader PRS-
 For usage information run the script.
 """
 
-import StringIO, sys, time, os, uuid
+import StringIO, sys, time, os
 from optparse import OptionParser
 
 from calibre import __version__, __appname__
@@ -213,7 +213,7 @@ def main():
 
     for d in connected_devices:
         try:
-            d.open(str(uuid.uuid4()))
+            d.open(None)
         except:
             continue
         else: