Comment 2 for bug 254035

I'm seeing this problem occur again, on my home machine running
debian/unstable. After I upgraded to the debian packaging of 0.6c8 (from
0.6c7), the tahoe build process started downloading and building a Nevow
tarball, even though there's a local copy already installed (with a
valid-looking .egg-info file) on sys.path .

http://allmydata.org/buildbot/builders/speed-DSL/builds/315/steps/compile/logs/stdio
is an example of the build process with setuptools-0.6c8, in which Nevow is
downloaded from divmod.org and compiled.

http://allmydata.org/buildbot/builders/speed-DSL/builds/312/steps/compile/logs/stdio
is an example of a build which failed because the local debian package of
nevow-0.9.29 was detected, which locked the target version at 0.9.29, and
setuptools then tried to download an 0.9.29 tarball (which failed because by
that point divmod.org was hosting a newer version, and so I presume they had
removed the old tarball).

http://allmydata.org/buildbot/builders/speed-DSL/builds/311/steps/compile/logs/stdio
is the first build with the new setuptools-0.6c8, doing the extra
download-and-build step.

http://allmydata.org/buildbot/builders/speed-DSL/builds/310/steps/compile/logs/stdio
is the last build with the old setuptools-0.6c7, in which it correctly
refrains from downloading or building Nevow.