Do not exclude .hg_archival.txt, mkversion.sh needs it.

debian/copyright

@@ -3,7 +3,7 @@ Upstream-Name: mbuffer
 Upstream-Contact: Thomas Maier-Komor <thomas@maier-komor.de>
 Source: https://www.maier-komor.de/mbuffer.html
 License: GPL-3+
-Files-Excluded: .hg_archival.txt .hgignore .hgtags
+Files-Excluded: .hgignore .hgtags
 
 Files: *
 Copyright: Copyright (C) 2000-2020, Thomas Maier-Komor

debian/watch

 version=4
-opts=repack,repacksuffix=+ds1,dversionmangle=s/\+ds.*//,pgpmode=none \
+opts=repack,repacksuffix=+ds2,dversionmangle=s/\+ds.*//,pgpmode=none \
 https://www.maier-komor.de/mbuffer.html .*software/mbuffer/mbuffer-(\d+)\.tgz