This only happens when the extra option "-e" is on (by default it is off).
Update the readme.txt in BaseTools package to specify the python source for MigrationMsa2Inf.
git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@3730 6f19259b-4bc3-4df7-8a09-765794883524