My attempt to track down the commit that introduced the glitches ended with the
following error from the configure script, using revisions "mesa-9.1" and
"mesa-9.0.3":

configure: error: DRI driver directory 'r300' does not exist

I followed the instructions given at the Ubuntu wiki site, using the configure
command with the parameters as listed below:

https://wiki.ubuntu.com/X/BisectingMesa

git clone git://anongit.freedesktop.org/git/mesa/mesa

...

./configure --prefix=/usr --mandir=\${prefix}/share/man \
    --infodir=\${prefix}/share/info --sysconfdir=/etc \
    --localstatedir=/var --build=i486-linux-gnu --disable-gallium
--with-driver=dri \
    --with-dri-drivers="r300" --with-demos=xdemos --libdir=/usr/lib/glx \
    --enable-glx-tls --enable-driglx-direct --disable-egl \
    --disable-glu --disable-glut --disable-glw CFLAGS="-Wall -g -O2"

To my understanding the particular driver "r300" is not (any longer?) part of
what I have cloned so far from the git repository, hence the configure script
wants to include a precompiled version. Could you please give me a hint how I
can get past this missing driver obstacle?

However opting out the parameter --with-dri-drivers="r300" enables the
configure script and subsequently the make command to succeed even though
glxgears, now running without artifacts at decent fps, is stuttering
noticeably. This applies to 9.0.3 and 9.1 likewise.