extensions: changed to call extsetup() from extensions.loadall()
previously uisetup() was invoked by extensions.loadall(), but
extsetup() was by _dispatch().
there's no need to split them because we have nothing to do
between uisetup() and extsetup().
this fixes
issue1824 indirectly.
adding foo
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
pushing to ../2
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files