Remove redundant line of code

Totally trivial.  A while back I added a line of code to the ROOT 6 to ignore a new harmless warning message from ROOT6.   Unbeknown to me, the same warning was also added to a later version of ROOT 5, so Chris Jones added effectively the same line of code in 7_1_X.  That just got carried forward into the ROOT6 branch, so it is now done twice.  This request removes the line that I added earlier to avoid doing the same thing twice, and to increase code commonality.