Add additional check of existence of environment before erasing it
Add additional check of existence of environment before erasing it

Change-Id: I0f73e8e064d13b1dbacc19c7bfad6a1a0b0d80e1
Closes-Bug: #1371496

SergK/fuel-main,ddepaoli3/fuel-main-dev,teselkin/fuel-main,Fiware/ops.Fuel-main-dev,AnselZhangGit/fuel-main,ddepaoli3/fuel-main-dev,huntxu/fuel-main,eayunstack/fuel-main,SmartInfrastructures/fuel-main-dev,zhaochao/fuel-main,AnselZhangGit/fuel-main,Fiware/ops.Fuel-main-dev,huntxu/fuel-main,eayunstack/fuel-main,huntxu/fuel-main,zhaochao/fuel-main,SmartInfrastructures/fuel-main-dev,dancn/fuel-main-dev,AnselZhangGit/fuel-main,SergK/fuel-main,zhaochao/fuel-main,SmartInfrastructures/fuel-main-dev,ddepaoli3/fuel-main-dev,stackforge/fuel-main,teselkin/fuel-main,teselkin/fuel-main,stackforge/fuel-main,teselkin/fuel-main,AnselZhangGit/fuel-main,SmartInfrastructures/fuel-main-dev,zhaochao/fuel-main,Fiware/ops.Fuel-main-dev,ddepaoli3/fuel-main-dev,stackforge/fuel-main,eayunstack/fuel-main,dancn/fuel-main-dev,dancn/fuel-main-dev,SergK/fuel-main,dancn/fuel-main-dev,zhaochao/fuel-main,Fiware/ops.Fuel-main-dev