On 1 September 2015 at 15:57, Rory McGuire via Digitalmars-d-announce <digitalmars-d-announce@puremagic.com> wrote:
On Tue, Sep 1, 2015 at 3:44 PM, Steven Schveighoffer via Digitalmars-d-announce <digitalmars-d-announce@puremagic.com> wrote:
[snip]
I'm not a dmd dev, but I'm not sure it will be accepted, since phobos is very unstable. We have to be cautious about making dmd breakable easily by a change to phobos.
[snip] 
-Steve

Surely this is a code coverage issue then?
Are there any unit tests  in ddmd?

From how I see it, Phobos is constantly adding, silently breaking, deprecating, and removing.  We need long term backwards compatibility, and Phobos just doesn't fit in that picture (yet).