emacs-21.1-21.2.diff: "the top of the Emacs source tree" is imprecise.

[Alan Mackenzie]

I recently downloaded the file emacs-21.1-21.2.diff from www.gnu.org.
The instructions in this file say "cd to the top of the emacs source tree
and then type 'sh <this file>'.

What exactly does "the top of the emacs source tree mean"?

My directory structure starts off /usr/src/packages/BUILD/, and directly
under this I have emacs-21.1 and emacs-21.2.  I created emacs-21.2 by
cloning emacs-21.1.

I then copied emacs-21.1-21.2.diff to /usr/..../BUILD/emacs-21.2/ and
attempted sh emacs-21.1-21.2.diff.

It didn't work.  More precisely, it didn't find all the files it needed
to patch, and prompted me to tell it where to find them.  I assume I must
have tried to run sh emacs-21.1-21.2.diff from the wrong place.

I think that the phrase ".. the top of emacs source tree .." is too
vague.  Is there any chance that the file comments can be elaborated to
state _exactly_ where it is to be copied to, where it is to be run from,
and what assumptions it makes on the shape of the source tree.

Thanks in advance.

-- 
Alan Mackenzie (Munich, Germany)
Email: aacm@muuc.dee; to decode, wherever there is a repeated letter
(like "aa"), remove half of them (leaving, say, "a").