Fix build.ps1 bug that when directory does not exist, copy-item in wrong behavior (#1595)
Fix build.ps1 bug that when directory does not exist, copy-item in wrong behavior (#1595)


pascalberger/docfx,pascalberger/docfx,hellosnow/docfx,dotnet/docfx,DuncanmaMSFT/docfx,928PJY/docfx,dotnet/docfx,dotnet/docfx,DuncanmaMSFT/docfx,928PJY/docfx,hellosnow/docfx,928PJY/docfx,superyyrrzz/docfx,pascalberger/docfx,hellosnow/docfx,superyyrrzz/docfx,superyyrrzz/docfx