Oh, as it turns out, the bug is there but not related to not finding
find/grep.

It IS actually finding the find.exe and grep.exe correctly using the
exec-path and/or (setenv "PATH" ..) hacks.

The problem was that the file was in a path with spaces in it:

C:\Users\kmodi\Desktop\_keep this folder empty\NEWS.txt

When I try using `A' in dired with above file marked and search for
"Emacs", I get "No matches for: Emacs". Note the spaces in the directory
name: "_keep this folder empty"

But when I copied NEWS.txt to C:\Users\kmodi\Desktop\NEWS.txt and then did
the same "Emacs" search using `A' in dired, it worked!

I can recreate this bug in RHEL too!

(1) mkdir -p /tmp/some\ dir
(2) Download http://git.savannah.gnu.org/cgit/emacs.git/plain/etc/NEWS as
/tmp/some\ dir/NEWS.txt
(3) In emacs -Q, use C-x d to open dired in /tmp/some\ dir/
(4) Mark NEWS.txt using `m' key
(5) Then I do `A' and search for "Emacs" (or probably anything else too)
(6) You should get "No matches for: Emacs"

Can you please rename the bug title to "25.0.93; dired-do-find-regexp does
not work when path contains spaces"?

Blocking bug?
-- 

-- 
Kaushal Modi