patch series versioning: please keep version numbers consistent

[Kevin Hilman <khilman@deeprootsystems.com>]

Hello,

If you are using version numbering in your patch series, please be
sure to update the version number for *all patches* in series.  Even
if only one patch of the series has changed in the updated series,
please update the version number for all patches.  Having different
version numbers within a series is confusing, and is more difficult to
follow when using automated tools such as patchworks.

Keeping versioning consistent is easy when using 'git format-patch'.
Simply use the --subject-prefix option to add a version number, and it
will be added to every patch in the series.  For example

  $ git format-patch -o tmp --subject-prefix='PATCH v3' <start>..<until>

Will ensure that all the subjects have the same versioning.

Kevin