StGit-enabled bash-prompt

[Robin Rosenberg <robin.rosenberg.lists@dewire.com>]

Hi,

I added the following snippet to my .bashrc to help me keep track of what 
patch I'm working on.  I got annoyed at typing stg top/stg series all the 
time.

This changes the bash prompt to include the current git branch and the top 
stgit patch to the prompt.

Of course you will read and understand this code. I don't know how good an 
idea it is to use the DEBUG trap this way.

NO WARRANTY (as always)

-- robin

if [ "$PS1" ]; then
    function stgtag
    {
        br=$(stg branch 2>/dev/null)
        top=$(stg top 2>/dev/null)
        if [[ -n "$br$top" ]];then
            echo " [$top@$br] "
        fi
    }
    trap 'PS1="\u@\h$(stgtag)\w]\$ "' DEBUG