Deprecation message from phobos compiling a vibe.d app.

[Martin Tschierschke via Digitalmars-d-learn]

When building my small vibe.d app I am getting this messages 
twice:

/usr/include/dmd/phobos/std/range/primitives.d(174,38): 
Deprecation: alias byKeyValue this is deprecated - Iterate over 
.byKeyValue instead.
/usr/include/dmd/phobos/std/range/primitives.d(176,27): 
Deprecation: alias byKeyValue this is deprecated - Iterate over 
.byKeyValue instead.
/usr/include/dmd/phobos/std/range/primitives.d(174,38): 
Deprecation: alias byKeyValue this is deprecated - Iterate over 
.byKeyValue instead.
/usr/include/dmd/phobos/std/range/primitives.d(176,27): 
Deprecation: alias byKeyValue this is deprecated - Iterate over 
.byKeyValue instead.

Unfortunately I don't know what is triggering this and what to do 
about.
The build is working, so it is more a question of elegance.