diff -Nru dpkg-1.18.4ubuntu1.1/debian/changelog dpkg-1.18.4ubuntu1.2/debian/changelog
--- dpkg-1.18.4ubuntu1.1/debian/changelog	2016-05-12 12:39:47.000000000 +0200
+++ dpkg-1.18.4ubuntu1.2/debian/changelog	2017-03-17 08:47:33.000000000 +0100
@@ -1,3 +1,12 @@
+dpkg (1.18.4ubuntu1.2) xenial; urgency=medium
+
+  * src/archives.c:
+    - handle a conffile moving from pkg-a to pkg-b correctly when
+      dpkg --root=/dir is used. Thanks to Guillem Jover.
+      LP: #1673247
+
+ -- Michael Vogt <michael.vogt@ubuntu.com>  Fri, 17 Mar 2017 08:47:33 +0100
+
 dpkg (1.18.4ubuntu1.1) xenial; urgency=medium
 
     * Add Breaks on ufw (<< 0.35-0ubuntu2~) for trigger loops (LP: #1571174)
diff -Nru dpkg-1.18.4ubuntu1.1/src/archives.c dpkg-1.18.4ubuntu1.2/src/archives.c
--- dpkg-1.18.4ubuntu1.1/src/archives.c	2015-12-12 21:49:37.000000000 +0100
+++ dpkg-1.18.4ubuntu1.2/src/archives.c	2017-03-17 08:47:20.000000000 +0100
@@ -853,14 +853,7 @@
              conff = conff->next) {
           if (!conff->obsolete)
             continue;
-          if (stat(conff->name, &stabtmp)) {
-            if (errno == ENOENT || errno == ENOTDIR || errno == ELOOP)
-              continue;
-            else
-              ohshite(_("cannot stat file '%s'"), conff->name);
-          }
-          if (stabtmp.st_dev == stab.st_dev &&
-              stabtmp.st_ino == stab.st_ino)
+          if (strcmp(conff->name, nifd->namenode->name) == 0)
             break;
         }
         if (conff) {