Improve: Avoid overwriting bytes in scratch buffer (part2)
Improve: Avoid overwriting bytes in scratch buffer (part2)

There was one corner case which was not considered correctly in the
orignial fix de1be2a Avoid overwriting bytes in scratch buffer. This
one corrects it. Initial internal tests suceeded on this one and
failed on the previous version.

ibm-genwqe/genwqe-user,ibm-genwqe/genwqe-user,tblume/genwqe-user,ferseiti/genwqe-user,ferseiti/genwqe-user,ibm-genwqe/genwqe-user,tblume/genwqe-user