bug#23659: 25.0.94; insert-file-contents with REPLACE gets confused by certain file contents

[Noam Postavsky <npostavs@users.sourceforge.net>]

[-- Attachment #1: Type: text/plain, Size: 654 bytes --]

Download all attached files into the same directory, then run

    emacs -Q -l test-insert-file-contents.el

The expected result is the text of "src" in "*a buffer*". The actual
result has the last line ending in "_SRE" instead of "_SRC".

I see this problem in 24.5 and 25.0.94, on both Windows and GNU/Linux.
Note that the test files "quote" and "src" have DOS line endings, and
don't have a newline at the end of the file.

This initially manifested as a yasnippet bug [1], it's easy to work
around though (just use `erase-buffer' instead of passing non-nil
REPLACE to `insert-file-contents').

[1]: https://github.com/joaotavora/yasnippet/issues/707

[-- Attachment #2: quote --]
[-- Type: application/octet-stream, Size: 107 bytes --]

# -*- require-final-newline: nil -*-
# name: org quote
# key: quote
# --
#+BEGIN_QUOTE
$0
#+END_QUOTE

[-- Attachment #3: src --]
[-- Type: application/octet-stream, Size: 102 bytes --]

# -*- require-final-newline: nil -*-
# name: org src
# key: src
# --
#+BEGIN_SRC $1
$0
#+END_SRC

[-- Attachment #4: test-insert-file-contents.el --]
[-- Type: application/octet-stream, Size: 199 bytes --]

(cd (file-name-directory (or load-file-name buffer-file-name)))
(switch-to-buffer "*a buffer*")
(erase-buffer)
(insert-file-contents "quote" nil nil nil t)
(insert-file-contents "src" nil nil nil t)