docker/docker — pull request #8276 by dqminh (2014-09-29 10:09:30+00:00)
Title: Fix #8262: check tag's validity before building.

When user passes an invalid tag to `docker build`, check the tag first and terminate-early so user can specify the tag again.

Docker-DCO-1.1-Signed-off-by: Daniel, Dao Quang Minh (github: dqminh)