Remove import which is unused according to pyflakes

mercurial_keyring.py

@@ -37,7 +37,7 b' command line). This extension uses and w'
 library.
 '''
 
-from mercurial import hg, util
+from mercurial import util
 from mercurial.i18n import _
 try:
     from mercurial.url import passwordmgr