> Same problem is on 5.5 where grep version is 2.5.1
Are you sure?
$ echo 'ASDFG' | grep '[a-z]'
Strange, but confirmed, happened also if compiled without all RH patches.
But probably it is not related to Bug #590002.
but NOT with:
Thus it is not the same issue as in Bug #590002 and the "Description of problem" is not valid.
Not my call, but I'd close this as NOTABUG.