contrib/linux-wheel-centos5-blacklist

template: compute verb in obsfateverb

Add a template function obsfateverb which use the markers information to
compute a better obsfate verb.

The current logic behind the obsfate verb is simple for the moment:

- If the successorsets is empty, the changeset has been pruned, for example:

    Obsfate: pruned

- If the successorsets length is 1, the changeset has been rewritten without
  divergence, for example:

    Obsfate: rewritten as 2:337fec4d2edc, 3:f257fde29c7a

- If the successorsets length is more than 1, the changeset has diverged, for
  example:

    Obsfate: split as 2:337fec4d2edc, 3:f257fde29c7a

As the divergence might occurs on a subset of successors, we might see some
successors twice:

    Obsfate: split as 9:0b997eb7ceee, 5:dd800401bd8c, 10:eceed8f98ffc; split
    as 8:b18bc8331526, 5:dd800401bd8c, 10:eceed8f98ffc

test-convert-git.t
test-subrepo-git.t
test-patchbomb-tls.t