gentoo-overlay/app-arch/dpkg/files/dpkg-1.18.12-rsyncable.patch

--- a/scripts/Dpkg/Compression.pm
+++ b/scripts/Dpkg/Compression.pm
@@ -81,20 +81,12 @@
 };
 
 #
-# XXX: The gzip package in Debian at some point acquired a Debian-specific
-# --rsyncable option via a vendor patch. Which is not present in most of the
-# major distributions, dpkg downstream systems, nor gzip upstream, who have
-# stated they will most probably not accept it because people should be using
-# pigz instead.
+# If gzip supports --rsyncable (version >=1.7 or the Debian patched variant),
+# we use it. Sadly a non-compliant gzip will not complain about the argument
+# when it does not understand it, so we can only print out the usage and infer
+# --rsyncable support from that.
 #
-# This option should have never been accepted in dpkg, ever. But removing it
-# now would probably cause demands for tarring and feathering. In addition
-# we cannot use the Dpkg::Vendor logic because that would cause circular
-# module dependencies. The whole affair is pretty disgusting really.
-#
-# Check the perl Config to discern Debian and hopefully derivatives too.
-#
-if ($Config{cf_by} eq 'Debian Project') {
+if (system("gzip --help 2>&1 | grep -q -- --rsyncable") == 0) {
     push @{$COMP->{gzip}->{comp_prog}}, '--rsyncable';
 }