Fix corner case assumption oops in env var reversion
Fix corner case assumption oops in env var reversion

Should not affect non-test usage.

tekapo/fabric,getsentry/fabric,TarasRudnyk/fabric,kxxoling/fabric,rane-hs/fabric-py3,cgvarela/fabric,raimon49/fabric,pashinin/fabric,sdelements/fabric,cmattoon/fabric,haridsv/fabric,ploxiln/fabric,bspink/fabric,jaraco/fabric,tolbkni/fabric,StackStorm/fabric,opavader/fabric,qinrong/fabric,amaniak/fabric,bitmonk/fabric,hrubi/fabric,MjAbuz/fabric,xLegoz/fabric,bitprophet/fabric,rodrigc/fabric,kmonsoor/fabric,askulkarni2/fabric,pgroudas/fabric,likesxuqiang/fabric,SamuelMarks/fabric,rbramwell/fabric,fernandezcuesta/fabric,itoed/fabric,elijah513/fabric,mathiasertl/fabric