Improve the logging of git_update
Improve the logging of git_update

Before:

   cd /apps/collectd-zservertracelog && git pull --ff-only
   # got commit abcdef12

After:

   cd /apps/collectd-zservertracelog
   git pull --ff-only
     # update 1234567..abcdef12

or

   cd /apps/collectd-zservertracelog
   git pull --ff-only
     # no changes

ProgrammersOfVilnius/pov-fabric-helpers