bash users created before pr4334 no longer have scripts from ~/.bashrc.d loaded

[TraceyC77]

A bug was fixed in this PR which has caused errors for bash users

The files in ~.bashrc.d had been incorrectly sourced for all shells from /usr/share/defaults/etc/profile
That had caused errors in other shells.
Unfortunately, correcting this means that existing users no longer have ~.bashrc.d sourced by /usr/share/defaults/etc/profile.

New users created after this change will have the scripts sourced normally from the files in skel

Come up with a one-off fix for users who existed before that change

Workaround for existing users

Add this to ~/.bashrc

# User specific bash aliases and functions
if [ -d ~/.bashrc.d ]; then
    for rc in ~/.bashrc.d/*; do
        if [ -f "$rc" ]; then
            . "$rc"
        fi
    done
    unset rc
fi