Is it true that dub compiles everything in the source dir whether it's imported or not?

[Gary Willoughby]

Is it true that dub compiles everything in the source dir whether 
it's imported or not?

Using it to compile a project that seems to be the case but i 
want to learn if that's true.

I draw this conclusion when investigating this problem: 
http://forum.dlang.org/thread/fvhdqcjfqfojzsyjpidl@forum.dlang.org?page=2#post-qavrnsytpszqiofgavgi:40forum.dlang.org

If it is true then perhaps dub needs to be re-engineered to only 
compile imported source files.