fix « cabal »'s bash-completion (see issue #5927)

[sboosali]

• ran shellcheck (a bash linter) on ./
• add shopt -s nullglob to _cabal_list_targets

tested manually (tabbing in a bash shell) and via shellcheck.

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[23Skidoo]

/cc @kolmodin

[23Skidoo]

@sboosali I don't use Bash completion, but the patch looks reasonable and I'm willing to trust you that this PR improves the current state of affairs.

@kolmodin Feel free to revert if you disagree.

[23Skidoo]

Merged, thanks!

[sboosali]

thanks!!

…

On Sat, Mar 9, 2019, 21:14 Mikhail Glushenkov ***@***.***> wrote: Merged, thanks! — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#5928 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/ACNoMTnGtGamwbA5rlWl3dFnC1PxVs0Gks5vVJTNgaJpZM4bkY7A> .