prevent importhook triggering on just 'import ROOT'; see ATEAM-597
The importhook by itself was OK, but in some cases it would cause a crash in XML parsing due to 2 conflicting copies of pyexpat.so in LCG_96
The importhook by itself was OK, but in some cases it would cause a crash in XML parsing due to 2 conflicting copies of pyexpat.so in LCG_96