From Philippe:

In TH1::Merge add support for merging histograms where bin labels are set
and not all bins or same bins have a label set.
This fixes the report: http://root.cern.ch/phpBB2/viewtopic.php?t=5767


git-svn-id: http://root.cern.ch/svn/root/trunk@24108 27541ba8-7e3a-0410-8455-c3a389f83636