When running python scripts via calibre-debug ensure that user plugins are loaded

src/calibre/debug.py

@@ -182,6 +182,9 @@ def main(args=sys.argv):
     from calibre.constants import debug
     debug()
     if len(args) > 2 and args[1] in ('-e', '--exec-file'):
+        import calibre.customize.ui as dummy # Load allplugins
+        dummy
+
         sys.argv = [args[2]] + args[3:]
         ef = os.path.abspath(args[2])
         base = os.path.dirname(ef)