bug#73142: Erroring libsixel package's bash completions for img2sixel

bug#73142: Erroring libsixel package's bash completions for img2sixel

[elaexuotee--- via Bug reports for GNU Guix]

Hey!

The recent move of libsixel into mpv's propagated-inputs surfaced a bug in
our libsixel's bash completions. My bash sessions now start with an error:

    -bash: have: Command not found

This was introduced in commit 43df0d83 from https://issues.guix.gnu.org/72180.
In particular, tracing with `set -o xtrace' show that it originates in the
first command of share/bash-completion/completions/img2sixel:

    have img2sixel

Upstream has a relevant issue: https://github.com/libsixel/libsixel/issues/81.
Our configuration step might need to set --with-bashcompltiondir.

- BW

bug#73142: Erroring libsixel package's bash completions for img2sixel

[elaexuotee--- via Bug reports for GNU Guix]

It appears that share/bash-compltion/bash_completion performs an
`unset -f have' at the end of the script. This means that only the scripts
under /etc/bash_completion.d/ have access to `have', but said directory doesn't
even exist in our case.

That said, `have' is deprecated in favor of `_have' in 2.11, anyway. I have let
upstream libsixel know, but we could work around the issue with a
single-character patch:

diff --git a/converters/shell-completion/bash/img2sixel b/converters/shell-completion/bash/img2sixel
index 028651b..d96a326 100644
--- a/converters/shell-completion/bash/img2sixel
+++ b/converters/shell-completion/bash/img2sixel
@@ -1,6 +1,6 @@
 # bash completion for img2sixel

-have img2sixel &&
+_have img2sixel &&
 _img2sixel()
 {
     local cur prev