Because revision specifies worktree state exactly, and if we have it
already, we don't need to fetch anything -- it is possible to
checkout/reset to the revision right away.

The reason for this patch is that fetching is sometimes not very fast or
even slow. For example today, gitlab.com had some outage and I've
developed this patch while waiting for it to come back.

/reviewed-by @jerome, @kazuhiko
/reviewed-on !1

This fixes this error:
[2015-04-10 06:28:09,906] INFO         exec self.options['script']
[2015-04-10 06:28:09,906] INFO       File "<string>", line 6, in <module>
[2015-04-10 06:28:09,906] INFO     NameError: name 'env' is not defined

When installing busybox

This reverts commit ab3bdcfb.

This reverts commit 9bd1e7e7.
What about test nodes ??
Why treating unpushed commits differently ?

commited-but-not-pushed changes will be lost.

Test is still failing due to recent unrelated changes.

By default we do not want to risk destroying developer's work.

The uninstall part was not working in webrunner environment where there
is not $PATH

Because it is the most important thing now in this egg.

To have logical output order, mostly for tests.

Both are compatible.

It allows to easily extend an existing section

This reverts commit 83632948.

This reverts commit 94446fa8.

This commit is blocking to set revision with branch equal master. It
means that the code below is not allowed.

[target]
revision = 1234
branch = master