Create .git/info directory if it does not exist before grafting

When cloning a new repository the directory .git/info does not
always exist. This change ensures this directory is always created
before trying to write to a file in that directory.

Change-Id: I9488caa7c4d0d80588ba880bee3bf9d8c11cca92
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>
complain about Reviewed-by footers

unlike previously thought, gerrit won't eliminate known bogus footers,
so they would stay behind. consequently, complain about them loudly.

note that the footers are just fine above a "(cherry picked from ...)"
line, as we want to preserve the original approvals.

Change-Id: I7856810adb3e3b3e91e539eb626375dd32648460
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
hint about Signed-off-by footers

we don't need them, as contributors do a pre-emptive sign-off on all their
contributions by agreeing with the CLA.

Change-Id: Ibab565370e00800dde7fddaa10a7aa21c332037f
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
complain about reverts with useless commit message

some people think a summary like "revert commit 124fa614423" is a good
idea. it's not - without researching the history, it is meaningless.

Change-Id: I6de02d911073aa2982ee05a6804db370a05d49e5
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
complain about bug references in summaries

they are redundant with the canonical Task-number footers and steal
precious space in the summary line.

Change-Id: I339c450d6322a7c403b097d880bff10c8167d973
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>