python-webpy: use webpy-0.39 tag
No functional change, but upstream has now tagged the release, so use the
tag instead of the sha1.
https://github.com/webpy/webpy/issues/449
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
(cherry picked from commit 01320bb9ff297bac38a4c9bc32ae505ac79d600f)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>