id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc
1	graph operations don't detect duplicate-label errors	nr	somebody	"Hoopl should detect a situation in which two graphs are spliced
and the labels of the blocks overlap.  At presesent, Hoopl uses
Data.IntSet.mapUnion and Data.IntSet.insert, neither of which
fails if a duplicate label appears.   Graph splicing and other
code needs to be modified to panic if labels overlap during splicing.
We therefore need something like
{{{

  unionWithKey (\l _ _ -> panic (""duplicate blocks with label "" ++ show l))
}}}
and similarly for insertion.
"	defect	new	minor		component1