Automatic dependency file generation bug/question

[ANDY KENNEDY <ANDY dot KENNEDY at adtran dot com>]

Reading <http://gcc.gnu.org/news/dependencies.html>, I find that
dependency files should be created along the lines of

%.o:  %.c ...

In gcc version 4.4.4 (Slackware64 Linux version 13.0), I execute the
following commands:

touch a.c
gcc -c -MMD -MP -MF"a.d" -MT"a.d" -o "a.o" "a.c"
cat a.c

and get the following output:

a.d a.o: a.c

which is precisely what I want.  However, I have a cross compiler using
gcc version 4.7.3 which produces the following output using the same
commands (obviously, with gcc replace with <path to >/bin/gcc:

a.d: a.c

I have been looking for the reason for the change, but am unable to find
the rational.

Please advise whether this is a bug, or if this is meant to be the way
gcc will work for all future releases.  As I see it, this complicates my
Makefile(s) as I have two gcc version that behave differently.  This
implies that my Makefile(s) will now require a section specifically
dedicated to the .d file generation.  Whereas I remember that this used
to be the way I had to construct the dependency list, this was
cumbersome and the way e.g. 4.4.4 supported automatic dependency
generation is preferable to me.

Thank you for your time,
Andy