We're using a property set to put the build number into our assemblies. When the build is run on the build server, the build number is passed in and everything is fine.
If the build is not specified externally, we set it to the current date and time, but this does not stay set in the property set, despite the build number variable being correct.
Attached is a simple build file showing the problem and a screenshot of part of the output.
I am able to reproduce the problem here, however the problem is that the fiversion fields are defined as In32, and yyyymmddhhMM will overflow the capacity of a 32 bit integer. Integer variables on the otherhand are treated as 64bit integers. I have changed the property sets to use 64bit integers, I’ll let you know when we have a build with the fix available (should be later today).
All components of the version must be integers greater than or equal to 0. Metadata restricts the major, minor, build, and revision components for an assembly to a maximum value of UInt16.MaxValue - 1. If a component exceeds this value, a compilation error occurs.”
So in essence what you are trying to do is not valid.