Thanks. Unfortunate that "git format-patch" cannot do "--follow" so there
will be no patch generated if we try to

    git format-patch ... lisp/obsolete/crisp.el.

since the last commit of crisp.el is to move it from emulation/ to
obsolete/. To generate a proper sequence for crisp.el we need to
find the commit ranges for crisp.el when it exists in emulation/.
I tried that and it worked. But later it turn out the "git log -p --follow"
method is a few steps simpler.Please refer to my reply to Stefan if
you're interested.
Thanks.