Fix SHA1 associated with SobolevSegmenter

The SHA was incorrect the previous time because I generated the
extension description file build the extension against my clone which
was having two remotes:

  origin: github.com/jcfr/SobolevSegmenter.git

  upstream: github.com/anry123/SobolevSegmenter.git

Since, origin/master hasn't updated, the description file generator
considered the latest commit associated with "origin" and not the one
associated with "upstream.

When generated, I noticed that the "scm" was incorrect, I manually fixed it
but I didn't consider the "revision".

Having tested that the extension was building locally, I assumed things
were correct.