Fixing Uscan failed: Filename pattern missing version delimiters () without filenamemangle

[Tong Sun <suntong001@users.sourceforge.net>]

Hi,

on my upstream's github-page there aren't any releases, thus I'm
having problem with updating the package:

---------------------------
$ gbp import-orig --sign-tags --uscan
gbp:info: Launching uscan...
uscan warn: Filename pattern missing version delimiters () without
filenamemangle
  in debian/watch, skipping:
  https://github.com/tonistiigi/fsutil.git HEAD debian
gbp:error: Uscan failed: Filename pattern missing version delimiters
() without filenamemangle
  in debian/watch, skipping:
  https://github.com/tonistiigi/fsutil.git HEAD debian

$ cat debian/watch
version=4
opts="mode=git, pgpmode=none" \
  https://github.com/tonistiigi/fsutil.git \
  HEAD debian

# Use the following when upstream starts to tag releases:
#
#version=4
#opts="filenamemangle=s%(?:.*?)?v?(\d[\d.]*)\.tar\.gz%golang-github-tonistiigi-fsutil-$1.tar.gz%,\
#      uversionmangle=s/(\d)[_\.\-\+]?(RC|rc|pre|dev|beta|alpha)[.]?(\d*)$/\$1~\$2\$3/"
\
#  https://github.com/tonistiigi/fsutil/tags .*/v?(\d\S*)\.tar\.gz debian

$ gbp import-orig --sign-tags --uscan --upstream-vcs-tag=f427cf1
gbp:info: Launching uscan...
uscan warn: Filename pattern missing version delimiters () without
filenamemangle
  in debian/watch, skipping:
  https://github.com/tonistiigi/fsutil.git HEAD debian
gbp:error: Uscan failed: Filename pattern missing version delimiters
() without filenamemangle
  in debian/watch, skipping:
  https://github.com/tonistiigi/fsutil.git HEAD debian
---------------------------

Again,

The upstream is https://github.com/tonistiigi/fsutil
and my repo is at
https://salsa.debian.org/go-team/packages/golang-github-tonistiigi-fsutil

Please help. thx.