What is src/emacs-22.0.50 for?

[Mark Plaksin]

After building CVS Emacs you have, src/emacs, src/emacs-22.0.50, and
src/emacs-22.0.50.1.  Why three?  What is the difference between them?  On
my GNU/Linux system (Debian unstable) the first and last are hard links to
each other.  Sample ls:

$ ls -li src/emacs{,-*}
24765 -rwxr-xr-x 2 happy happy  9378548 Jan 14 10:23 src/emacs*
21633 -rwxr-xr-x 1 happy happy 13622004 Jan 14 10:09 src/emacs-22.0.50*
24765 -rwxr-xr-x 2 happy happy  9378548 Jan 14 10:23 src/emacs-22.0.50.1*

One difference that I stumbled upon is that the emacs-22.0.50 binary breaks
documentation for functions defined in the C source.  At some point I
accidentally symlinked ~/bin/emacs to src/emacs-22.0.50 in one of my build
trees.  I always invoke emacs as ~/bin/emacs.  Later I noticed that
describe-function always said "Missing arg list" when I requested
documentation for a function defined in C.  Is that expected or is it a
bug?

To reproduce:

Run src/emacs -q and then C-h f make-network-process RET.  You will get the
documentation for make-network process.

Then run src/emacs-22.0.50 -q and C-h f make-network-process RET. You
will get:

  make-network-process is a built-in function in `C source code'.
  [Missing arglist.  Please make a bug report.]
  
  Not documented.