rBuffer.size() of 26, nBytes of 25, rBuffer[25] is the first zero
so aLine.getLength() of 25, nBytes reduced by aLine.getLength()+1 and
nRun increased by same, so nBytes wraps and nRun is 26.

Change-Id: Ia9f4789e081e6b77a21321f37d71cabfc7c84550
Reviewed-on: https://gerrit.libreoffice.org/56478
Tested-by: Jenkins
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>