Fix crash with insert-file-contents and misdecoded text.

* fileio.c (Finsert_file_contents): Set CODING_MODE_LAST_BLOCK
before invoking decode_coding_gap, since there's just one block.

Fixes: debbugs:16286

src/ChangeLog

+2014-01-26  Paul Eggert  <eggert@cs.ucla.edu>
+
+	Fix crash with insert-file-contents and misdecoded text (Bug#16286).
+	* fileio.c (Finsert_file_contents): Set CODING_MODE_LAST_BLOCK
+	before invoking decode_coding_gap, since there's just one block.
+
 2014-01-25  Martin Rudalics  <rudalics@gmx.at>
 
 	Fix handling of face attributes in Fx_create_frame (Bug#16529).

src/fileio.c

@@ -4298,6 +4298,7 @@ by calling `format-decode', which see.  */)
       Z_BYTE -= inserted;
       ZV -= inserted;
       Z -= inserted;
+      coding.mode |= CODING_MODE_LAST_BLOCK;
       decode_coding_gap (&coding, inserted, inserted);
       inserted = coding.produced_char;
       coding_system = CODING_ID_NAME (coding.id);