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