The file ~/.bashrc , identically /etc/skel/.bashrc ,
currently sources ~/.bash_aliases BEFORE setting up the
programmable completion features
(/usr/share/bash-completion/bash_completion or
/etc/bash_completion )

It would be better if ~/.bash_aliases is sourced AFTER
setting up bash-completion, so that that the user's file can
modify the bash-completion features after they have been set
up.  Currently, anything done regarding completion in
~/.bash_aliases gets clobbered by the system.

~/.bash_aliases should be the very last thing in ~/.bashrc .
The general idea is to allow the user to modify ~/.bashrc as
little as possible (to make it easy to pick up any changes
after upgrades), so to allow the user to only need to make
local changes to ~/.bash_aliases .

Attached is a patch to the source.