Bash completion for Inkscape does not work

Bash completion for Inkscape does not work in Ubuntu 18.04. It will for example suggest non-svg files.

The reason seems to be that /usr/share/bash-completion/completions/inkscape uses the have() function, which is temporarily defined in /usr/share/bash-completion/bash_completion, but then unset at the end of that file.

Workaround: Copy /usr/share/bash-completion/completions/inkscape to ~/.local/share/bash-completion/completions/inkscape and remove the uses of "have".

The bash completion for some other commands seem to use have() too, e.g. jackd, ufw, cowbuilder, dpatch_edit_patch, and axi-cache, so bash completion for these commands will presumably not work either.

From /usr/share/bash-completion/bash_completion:
-----------------------------------------------------------------------------
# Backwards compatibility for compat completions that use have().
# @deprecated should no longer be used; generally not needed with dynamically
# loaded completions, and _have is suitable for runtime use.
have()
{
    unset -v have
    _have $1 && have=yes
}
[...]
unset -f have
unset have
-----------------------------------------------------------------------------

From /usr/share/bash-completion/completions/inkscape:
-----------------------------------------------------------------------------
[...]
have inkscape &&
_inkscape()
{
  [...]
}
[ "${have:-}" ] && complete -F _inkscape $filenames inkscape
-----------------------------------------------------------------------------

System information:

$ lsb_release -rd
Description: Ubuntu 18.04.1 LTS
Release: 18.04

$ apt-cache policy inkscape
inkscape:
  Installed: 0.92.3-1
  Candidate: 0.92.3-1
  Version table:
 *** 0.92.3-1 500
        500 http://no.archive.ubuntu.com/ubuntu bionic/universe amd64 Packages
        100 /var/lib/dpkg/status