bug#4708: 23.1; completion-try-completion adds an extra $: $$HOMj

[Drew Adams]

emacs -Q
 
M-: (completion-try-completion "c:/some-dir/$HOMj" nil 16)
 
correctly returns: (c:/some-dir/$HOMEj" . 17)
 
M-: (completion-try-completion "c:/some-dir/$HOMj" nil 17)
 
returns: ("c:/some-dir/$$HOMj" . 18)
 
That doesn't seem correct. Is it correct to have $$ here? If so, can
you please explain it a bit (why)?
 
Also, if this is correct behavior, then please explain this in the doc
string of `completion-try-completion'. The doc string currently says
that STRING, in the return value of (STRING . NEWPOINT), is "the
completed result string". But "result string" cannot be right, if
we're talking about the result of completion. There is no completion
that contains $$HOM.
 
In GNU Emacs 23.1.1 (i386-mingw-nt5.1.2600)
 of 2009-07-29 on SOFT-MJASON
Windowing system distributor `Microsoft Corp.', version 5.1.2600
configured using `configure --with-gcc (4.4)'