config: use single quotes around command hint

Windows command lines use double quotes to quote arguments with spaces.
This change is in a series to unify around using single quotes around
commands, and double quotes around interior arguments.

mercurial/ui.py

@@ -583,7 +583,7 b' class ui(object):'
                 pass
         if not user:
             raise error.Abort(_('no username supplied'),
-                             hint=_('use "hg config --edit" '
+                             hint=_("use 'hg config --edit' "
                                     'to set your username'))
         if "\n" in user:
             raise error.Abort(_("username %s contains a newline\n")

tests/test-commit-interactive.t

@@ -291,7 +291,7 b' Modify end of plain file with username u'
   $ unset HGUSER
   $ hg commit -i --config ui.username= -d '8 0' -m end plain
   abort: no username supplied
-  (use "hg config --edit" to set your username)
+  (use 'hg config --edit' to set your username)
   [255]
 
 

tests/test-committer.t

@@ -50,7 +50,7 b''
   $ echo "username = " >> .hg/hgrc
   $ hg commit -m commit-1
   abort: no username supplied
-  (use "hg config --edit" to set your username)
+  (use 'hg config --edit' to set your username)
   [255]
 
 # test alternate config var