Fix bug#16286 by the different way than 2014-01-26T00:32:30Z!eggert@cs.ucla.edu to preserve the code detection behavior of 24.3.

1 files changed, 4 insertions, 2 deletions

diff --git a/src/coding.c b/src/coding.c
index 01964eba4d3..654e39c0e3d 100644
--- a/src/coding.c
+++ b/src/coding.c
@@ -1300,6 +1300,7 @@ detect_coding_utf_8 (struct coding_system *coding,
            means that we found a valid non-ASCII characters.  */
         detect_info->found |= CATEGORY_MASK_UTF_8_AUTO | CATEGORY_MASK_UTF_8_NOSIG;
     }
+  coding->detected_utf8_bytes = src_base - coding->source;
   coding->detected_utf8_chars = nchars;
   return 1;
 }
@@ -7890,7 +7891,7 @@ decode_coding_gap (struct coding_system *coding,
   coding->dst_multibyte = ! NILP (BVAR (current_buffer, enable_multibyte_characters));
 
   coding->head_ascii = -1;
-  coding->detected_utf8_chars = -1;
+  coding->detected_utf8_bytes = coding->detected_utf8_chars = -1;
   coding->eol_seen = EOL_SEEN_NONE;
   if (CODING_REQUIRE_DETECTION (coding))
     detect_coding (coding);
@@ -7907,7 +7908,8 @@ decode_coding_gap (struct coding_system *coding,
       if (chars != bytes)
         {
           /* There exists a non-ASCII byte.  */
-          if (EQ (CODING_ATTR_TYPE (attrs), Qutf_8))
+          if (EQ (CODING_ATTR_TYPE (attrs), Qutf_8)
+              && coding->detected_utf8_bytes == coding->src_bytes)
             {
               if (coding->detected_utf8_chars >= 0)
                 chars = coding->detected_utf8_chars;