fix stress issue in nuget packageextractor
fix stress issue in nuget packageextractor

if mutex.WaitOne returns false, you don't own the mutex.
If you don't own it, you can't release it (exception thrown).
cf http://msdn.microsoft.com/en-us/library/system.threading.mutex.releasemutex.aspx

cr: feiling

oliver-feng/nuget,jholovacs/NuGet,mono/nuget,dolkensp/node.net,GearedToWar/NuGet2,rikoe/nuget,oliver-feng/nuget,mrward/NuGet.V2,xoofx/NuGet,chocolatey/nuget-chocolatey,RichiCoder1/nuget-chocolatey,ctaggart/nuget,akrisiun/NuGet,mrward/NuGet.V2,indsoft/NuGet2,OneGet/nuget,chocolatey/nuget-chocolatey,jmezach/NuGet2,mrward/NuGet.V2,alluran/node.net,alluran/node.net,jmezach/NuGet2,antiufo/NuGet2,RichiCoder1/nuget-chocolatey,dolkensp/node.net,indsoft/NuGet2,jholovacs/NuGet,dolkensp/node.net,RichiCoder1/nuget-chocolatey,ctaggart/nuget,ctaggart/nuget,jmezach/NuGet2,pratikkagda/nuget,pratikkagda/nuget,RichiCoder1/nuget-chocolatey,pratikkagda/nuget,mrward/nuget,jmezach/NuGet2,rikoe/nuget,rikoe/nuget,jholovacs/NuGet,oliver-feng/nuget,antiufo/NuGet2,OneGet/nuget,pratikkagda/nuget,GearedToWar/NuGet2,pratikkagda/nuget,mrward/NuGet.V2,jholovacs/NuGet,GearedToWar/NuGet2,dolkensp/node.net,indsoft/NuGet2,chocolatey/nuget-chocolatey,alluran/node.net,RichiCoder1/nuget-chocolatey,indsoft/NuGet2,GearedToWar/NuGet2,antiufo/NuGet2,chocolatey/nuget-chocolatey,jholovacs/NuGet,OneGet/nuget,mono/nuget,mrward/nuget,antiufo/NuGet2,mrward/nuget,chocolatey/nuget-chocolatey,OneGet/nuget,mrward/NuGet.V2,RichiCoder1/nuget-chocolatey,antiufo/NuGet2,jmezach/NuGet2,mrward/nuget,oliver-feng/nuget,xoofx/NuGet,mrward/nuget,xoofx/NuGet,jmezach/NuGet2,xoofx/NuGet,jholovacs/NuGet,oliver-feng/nuget,chocolatey/nuget-chocolatey,akrisiun/NuGet,mono/nuget,pratikkagda/nuget,GearedToWar/NuGet2,rikoe/nuget,mrward/nuget,indsoft/NuGet2,mono/nuget,oliver-feng/nuget,indsoft/NuGet2,xoofx/NuGet,mrward/NuGet.V2,alluran/node.net,ctaggart/nuget,antiufo/NuGet2,xoofx/NuGet,GearedToWar/NuGet2