Files collection of full path is flakey

[loudej]

Files.Include(xxx) when xxx has a full path doesn't really work like you would expect

It produces an error (on Mac at least) because it seems to append the current directory in front of the xxx directory (because it thinks it's a relative path?) and that throws an error because the total combined path doesn't exist.

[dragan]

Think we're hitting this bug when running the build on the CI server, under the Mono Build Agent.

[dragan]

Here's the build log.