Fix backward compatibility of PullRequestSCMRevision

[andrey-fomin]

Method getPull is used in some private plugins.
#796 changed signature of this method.

Now signature is returned back.
See also #817.

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[rsandell]

Thanks for the alternative approach, the small risk with this approach is that potentially some places might already have adapted to the new signature that is already in a couple of releases. And now it would be changed back again. So I think my approach is slightly safer.

[basil]

Yes safer in the short-term, but less maintainable in the long term since the bridge method injector is some complicated magic and only used in a handful of plugins. No strong preference, but I can see the wisdom in biting the bullet now with this approach (and dealing with any fallout) in order to avoid the long-term dependency on the bridge method injector.

[andrey-fomin]

#817 was merges. So closing this one.