segfault while setting non-cubic reciprocal lattice.

[abuts]

The code below segfaults Mantid on SetupUB while inverting some internal matrix.

WS_Name = 'CNCS_7860_event'
Load(Filename='CNCS_7860_event.nxs',OutputWorkspace=WS_Name )

AddSampleLog(Workspace=WS_Name,LogName='Ei',LogText='3',LogType='Number')
MD_Name='MD1'
SetUB(Workspace=WS_Name,a='10.4165',b='3.4165',c='10.4165',alpha=30,beta=45,gamma=80,u='1,0,0',v='0,1,0')
ConvertToMDEvents(InputWorkspace=WS_Name,OutputWorkspace=MD_Name,QDimensions='QhQkQl',QinHKL=False,dEAnalysisMode='Direct',MinValues='-2,-2,-3,-1',MaxValues='2,2,3,3',SplitInto="20,20,20,1")
ps=plotSlice(MD_Name, xydim=["Q1","Q2"], slicepoint=[0,0] )

[abuts]

This issue was originally trac ticket 4679