set seedCollection= nullptr before leaving the scope, else would assert/crash next call
Merge pull request #5022 from slava77/CMSSW_7_2_X_2014-08-20-0200/fix720pre4assert-conversionOneLeg

fix crash in pre4 Assertion `seedCollection==nullptr' failed.
Merge remote branch 'origin/CMSSW_7_2_X' into CMSSW_7_0_X