Don't sample between energy distributions if there's only one
Don't sample between energy distributions if there's only one

smharper/openmc,smharper/openmc,samuelshaner/openmc,walshjon/openmc,bhermanmit/openmc,mit-crpg/openmc,johnnyliu27/openmc,shikhar413/openmc,paulromano/openmc,amandalund/openmc,samuelshaner/openmc,wbinventor/openmc,samuelshaner/openmc,bhermanmit/openmc,paulromano/openmc,shikhar413/openmc,smharper/openmc,amandalund/openmc,liangjg/openmc,paulromano/openmc,amandalund/openmc,liangjg/openmc,johnnyliu27/openmc,shikhar413/openmc,liangjg/openmc,wbinventor/openmc,johnnyliu27/openmc,shikhar413/openmc,wbinventor/openmc,liangjg/openmc,amandalund/openmc,walshjon/openmc,walshjon/openmc,wbinventor/openmc,samuelshaner/openmc,mit-crpg/openmc,paulromano/openmc,walshjon/openmc,mit-crpg/openmc,mit-crpg/openmc,smharper/openmc,johnnyliu27/openmc