dub set default compiler for project

[Nicholas Wilson via Digitalmars-d-learn]

dub build has the --compiler= option.
Is there any way to set it to default a custom  version (own 
branch, resides in ../../ldcbuild/bin/ldc2 ) of ldc2 in the 
dub.json (or .sdl)?
 The project will only compile with that compiler.