Bug: pager.<cmd> doesn't work well with editors

[Anatoly Borodin <anatoly.borodin@gmail.com>]

Hi All!

It can be useful to enable `pager.branch`, `pager.tag`, `pager.config`, etc
for some projects (`git` itself can be a good example, with all its feature
branches and tags).

But it makes commands like `git branch --edit-description`, `git tag -a`,
`git config -e` extremely unhappy. For example, `vim` says

	Vim: Warning: Output is not to a terminal

and then becomes unusable (just as `vim | less` would be).

I think, the pagination should be turned off when the editor is being
called.

-- 
Mit freundlichen Grüßen,
Anatoly Borodin