Replicating the default "git log" format with a format string.

For our workflow, author dates aren't very useful.  I'm looking for a way to
configure Git so that "git log" shows commit dates instead of author dates.
 "--pretty=fuller" gets me almost what I want, but I'd like to avoid the
extra two lines if possible.

I tried achieving this by putting a custom format string in ~/.gitconfig:

[format]
  pretty = "%C(auto,yellow)commit %C(auto)%H\nAuthor: %an <%ae>\nDate:  
%cd\n\n%w(0,4,4)%B"

This works pretty well, but has a few corner cases. When you do "git log --decorate", the default format decorates commits with ref names. I can add "%d" to my format string, but then the ref names show up all the time, even without "--decorate".

The "--walk-reflogs" option presents a similar problem. The %g* placeholders all become empty strings when "--walk-reflogs" isn't present, which is sort of what I want, but it leaves extra blank lines in the output.

Is it possible to exactly replicate the default "git log" format with a format string?