Move line from output to the front of output or custom reordering

I'm not sure I understand what you're trying to do here but if all you want is to have the line with /openerp/addons to be first and /web/addons to be second, why not just something like this:

find "$PWD" -name '__openerp__.py' | awk -F/ -vOFS=/ 'NF-=2' | 
  sed 's#^\(.*/openerp/addons.*\)#aaa%\1#; s#^\(.*/web/addons.*\)#aab%\1#' | 
   sort -u | sed 's/^aa.%//'

Not particularly clever or elegant but this will simply add aaa% to the beginning of lines containing /openerp/addons and aab% to the beginning of lines containing /web/addons. The last sed removes them again after sorting. Assuming you have no files whose name starts with aa.%, that should have the desired result.

Or, you could use a simple perl one-liner that also does the job of sort -u:

find fafa/ | awk -F/ -vOFS=/ 'NF-=2' | 
 perl -ne 's#^(.*/openerp/addons)#aaa%$1#; s#^(.*/web/addons)#aab%$1#; $k{$_}++; 
            END{for (sort keys(%k)){s/^aa.%//; print }}'

As I mentioned in a comment, pipelines are not the way to go; at least not with a tool as simple as grep. I would use a more powerful tool, such as Python or Perl, for this. Here's a Perl filter that might help:

your command | perl -ne '
    if($already_found_lines){
        print # print the current line as is
    } else{
        if   (m{/web/addons}    ) { $web=$_     and $found_web++    }
        elsif(m{/openerp/addons}) { $openerp=$_ and $found_openerp++}
        else                      { push @buffer,$_                 }
        $already_found_lines = ($found_web and $found_openerp);
        if($already_found_lines)  { print "${openerp}$web";print for @buffer}
    }'

This tested correctly with your sample input.