Bug#873277: sometimes environment variables do not expand

[積丹尼 Dan Jacobson]

Package: bash-completion
Version: 1:2.1-4.3

Normally $BR<TAB> expands to $BROWSER for me. Except here!:
$ apt-cache show $@|perl -wlne 'print for /http\S+/g'|sort -u|xargs $BR<TAB>