diff -Nru dpkg-1.17.5ubuntu5.7/debian/changelog dpkg-1.17.5ubuntu5.8/debian/changelog
--- dpkg-1.17.5ubuntu5.7/debian/changelog	2016-06-14 18:31:28.000000000 +0000
+++ dpkg-1.17.5ubuntu5.8/debian/changelog	2017-12-04 19:15:45.000000000 +0000
@@ -1,3 +1,10 @@
+dpkg (1.17.5ubuntu5.8) trusty; urgency=medium
+
+  * Add support for .deb archives with a control member not compressed
+    (control.tar) or compressed with xz (control.tar.xz) LP: #1730627.
+
+ -- Adam Conrad <adconrad@ubuntu.com>  Mon, 04 Dec 2017 12:15:45 -0700
+
 dpkg (1.17.5ubuntu5.7) trusty; urgency=medium
 
   * Backport from Debian (LP: #1587667):
diff -Nru dpkg-1.17.5ubuntu5.7/dpkg-deb/build.c dpkg-1.17.5ubuntu5.8/dpkg-deb/build.c
--- dpkg-1.17.5ubuntu5.7/dpkg-deb/build.c	2013-12-10 06:15:02.000000000 +0000
+++ dpkg-1.17.5ubuntu5.8/dpkg-deb/build.c	2017-12-04 19:15:31.000000000 +0000
@@ -558,10 +558,14 @@
              debar, err.str);
   } else if (deb_format.major == 2) {
     const char deb_magic[] = ARCHIVEVERSION "\n";
+    char adminmember[16 + 1];
+
+    sprintf(adminmember, "%s%s", ADMINMEMBER,
+            compressor_get_extension(compressor_type_gzip));
 
     dpkg_ar_put_magic(debar, arfd);
     dpkg_ar_member_put_mem(debar, arfd, DEBMAGIC, deb_magic, strlen(deb_magic));
-    dpkg_ar_member_put_file(debar, arfd, ADMINMEMBER, gzfd, -1);
+    dpkg_ar_member_put_file(debar, arfd, adminmember, gzfd, -1);
   } else {
     internerr("unknown deb format version %d.%d", deb_format.major, deb_format.minor);
   }
diff -Nru dpkg-1.17.5ubuntu5.7/dpkg-deb/dpkg-deb.h dpkg-1.17.5ubuntu5.8/dpkg-deb/dpkg-deb.h
--- dpkg-1.17.5ubuntu5.7/dpkg-deb/dpkg-deb.h	2013-12-10 06:14:22.000000000 +0000
+++ dpkg-1.17.5ubuntu5.8/dpkg-deb/dpkg-deb.h	2017-12-04 19:15:31.000000000 +0000
@@ -70,7 +70,7 @@
 #define OLDOLDDEBDIR		".DEBIAN"
 
 #define DEBMAGIC		"debian-binary"
-#define ADMINMEMBER		"control.tar.gz"
+#define ADMINMEMBER		"control.tar"
 #define DATAMEMBER		"data.tar"
 
 #define MAXFILENAME 2048
diff -Nru dpkg-1.17.5ubuntu5.7/dpkg-deb/extract.c dpkg-1.17.5ubuntu5.8/dpkg-deb/extract.c
--- dpkg-1.17.5ubuntu5.7/dpkg-deb/extract.c	2015-11-26 12:57:29.000000000 +0000
+++ dpkg-1.17.5ubuntu5.8/dpkg-deb/extract.c	2017-12-04 19:15:31.000000000 +0000
@@ -178,9 +178,18 @@
         if (fd_skip(arfd, memberlen + (memberlen & 1), &err) < 0)
           ohshit(_("cannot skip archive member from '%s': %s"), debar, err.str);
       } else {
-	if (strncmp(arh.ar_name, ADMINMEMBER, sizeof(arh.ar_name)) == 0)
+        if (strncmp(arh.ar_name, ADMINMEMBER, strlen(ADMINMEMBER)) == 0) {
+          const char *extension = arh.ar_name + strlen(ADMINMEMBER);
+
 	  adminmember = 1;
-	else {
+          decompressor = compressor_find_by_extension(extension);
+          if (decompressor != compressor_type_none &&
+              decompressor != compressor_type_gzip &&
+              decompressor != compressor_type_xz)
+            ohshit(_("archive '%s' uses unknown compression for member '%.*s', "
+                     "giving up"),
+                   debar, (int)sizeof(arh.ar_name), arh.ar_name);
+        } else {
           if (adminmember != 1)
             ohshit(_("archive '%s' has premature member '%.*s' before '%s', "
                      "giving up"),
diff -Nru dpkg-1.17.5ubuntu5.7/man/deb.5 dpkg-1.17.5ubuntu5.8/man/deb.5
--- dpkg-1.17.5ubuntu5.7/man/deb.5	2013-12-10 06:14:22.000000000 +0000
+++ dpkg-1.17.5ubuntu5.8/man/deb.5	2017-12-04 19:15:31.000000000 +0000
@@ -66,8 +66,11 @@
 in the archive (except at the end), as described below.
 .PP
 The second required member is named
-.BR control.tar.gz .
-It is a gzipped tar archive containing the package control information,
+.BR control.tar .
+It is a tar archive containing the package control information, either
+not compressed (supported since dpkg 1.17.6), or compressed with
+gzip (with \fB.gz\fP extension) or
+xz (with \fB.xz\fP extension, supported since 1.17.6),
 as a series of plain files, of which the file
 .B control
 is mandatory and contains the core control information. The control