Fixing is_disk() which mistakes devices with name longer than 20 chars for partitions.

Associated with previous vmstat -d enhancement commit.
1 job for <span class="ref-name">vmstat_isdev_fix</span> in 2 minutes and 31 seconds (queued for 11 seconds)
Status Job ID Name Coverage
  Test
passed #3342089
MakeCheck

00:02:31