Calm down Vim's default syntax highlighter

When case is left without quotes, Vim's default syntax highlighter shows
the left bracket in strong, error-y red style (not sure why, e.g.
ShellCheck does not complain about that notation).  It seems to work
fine when quoted, though.

dotfiles/bash/post.bashrc

     # http://www.davidpashley.com/articles/xterm-titles-with-bash.html
     #
     case "$BASH_COMMAND" in
-        *\033]0*)
+        *"\033]"0*)
             # The command is trying to set the title bar as well;
             # this is most likely the execution of $PROMPT_COMMAND.
             # In any case nested escapes confuse the terminal, so don't