Check for prepended backslashes in user-supplied flags

lib/imap.js

@@ -1157,10 +1157,13 @@ ImapConnection.prototype._store = function(which, uids, flags, isAdding, cb) {
     flags = [flags];
   for (var i=0; i<flags.length; i++) {
     if (!isKeywords) {
+      if (flags[i][0] === '\\')
+        flags[i] = flags[i].substr(1);
       if (this._state.box.permFlags.indexOf(flags[i]) === -1
-          || flags[i] === '\\*' || flags[i] === '*')
+          || flags[i] === '*')
         throw new Error('The flag "' + flags[i]
                         + '" is not allowed by the server for this mailbox');
+      flags[i] = '\\' + flags[i];
     } else {
       // keyword contains any char except control characters (%x00-1F and %x7F)
       // and: '(', ')', '{', ' ', '%', '*', '\', '"', ']'
@@ -1170,8 +1173,6 @@ ImapConnection.prototype._store = function(which, uids, flags, isAdding, cb) {
       }
     }
   }
-  if (!isKeywords)
-    flags = flags.map(function(flag) {return '\\' + flag;});
   flags = flags.join(' ');
   cb = arguments[arguments.length-1];