bug#1809: decode-coding-inserted-region corrupts files

[Juri Linkov]

Below is a shorter test case simplified from `epa-file-decode-and-insert':

1. emacs -Q

2. Evaluate

(progn
  (switch-to-buffer "test")
  (insert "Test.\nTest2.\nTest3.\n")
  (decode-coding-inserted-region
   (point-min) (point-max) "/tmp/test" t nil nil nil))

3. The first character becomes the NULL control character:

^@est.
Test2.
Test3.

-- 
Juri Linkov
http://www.jurta.org/emacs/