dpkg-deb: Count one missing warning() for the total amount reported

debian/changelog

@@ -13,6 +13,7 @@ dpkg (1.16.0) UNRELEASED; urgency=low
     to its standard input. Suggested by Raphaël Hertzog.
   * Add missing space in update-alternative --set-selections output.
   * Add missing options to update-alternative --help output.
+  * Count “conffile name is duplicated” for dpkg-deb warning count summary.
 
   [ Raphaël Hertzog ]
   * Fail properly when debian/source/format is empty. Closes: #600854

dpkg-deb/build.c

@@ -308,9 +308,10 @@ check_conffiles(const char *dir)
       warns++;
     }
 
-    if (file_info_find_name(conffiles_head, conffilename))
+    if (file_info_find_name(conffiles_head, conffilename)) {
       warning(_("conffile name '%s' is duplicated"), conffilename);
-    else {
+      warns++;
+    } else {
       struct file_info *conffile;
 
       conffile = file_info_new(conffilename);