On Wednesday 06 August 2014 05:04:48 David Fifield wrote:
You probably need to kill your qemu process and start "build-alpha" again. See: https://trac.torproject.org/projects/tor/wiki/doc/TorBrowser/BuildingWithGit ian#AssemblyErrorsinMismatchedArchitectureCode
Thanks David for pointing me to that document. Killing qemu resolved the issue.