Makefile: Strip 'heads/' from git rev-parse --abbrev-ref HEAD
Makefile: Strip 'heads/' from git rev-parse --abbrev-ref HEAD

  git rev-parse --abbrev-ref HEAD can return results in a couple different ways:
  1) tag v1.1.0-rc3 exists and branch==v1.1.0-rc3
     result: heads/v1.1.0-rc3
  2) tag v1.1.0-rc3 doesn't exist and branch==v1.1.0-rc3
     result: v1.1.0-rc3

  Strip it off GIT_BRANCH regardless as it will break the build.  e.g.

  $ make binary
  docker build  -t "traefik-dev:heads/v1.1.0-rc3" -f build.Dockerfile .
  invalid value "traefik-dev:heads/v1.1.0-rc3" for flag -t: Error parsing reference: "traefik-dev:heads/v1.1.0-rc3" is not a valid repository/tag
  See 'docker build --help'.
  Makefile:51: recipe for target 'build' failed
  make: *** [build] Error 125

mmatur/traefik,yyekhlef/traefik,seryl/traefik,vdemeester/traefik,simbas/traefik,FriggaHel/traefik,nmengin/traefik,lewisheadden/traefik,mvdstam/traefik,tanyadegurechaff/traefik,adityacs/traefik,kekoav/traefik,thomasbach76/traefik,mildis/traefik,lewisheadden/traefik,yyekhlef/traefik,Regner/traefik,seryl/traefik,simbas/traefik,nmengin/traefik,martinbaillie/traefik,atbore-phx/traefik,thomasbach76/traefik,Regner/traefik,adityacs/traefik,vholovko/traefik,jangie/traefik,vdemeester/traefik,owen/traefik,vholovko/traefik,containous/traefik,yyekhlef/traefik,nmengin/traefik,timoreimann/traefik,owen/traefik,CyrilPeponnet/traefik,mildis/traefik,carriercomm/traefik,martinbaillie/traefik,mihaitodor/traefik,tanyadegurechaff/traefik,ldez/traefik,ldez/traefik,mvdstam/traefik,dtomcej/traefik,aantono/traefik,SantoDE/traefik,jangie/traefik,CyrilPeponnet/traefik,timoreimann/traefik,SantoDE/traefik,owen/traefik,CyrilPeponnet/traefik,jangie/traefik,containous/traefik,akanto/traefik,tanyadegurechaff/traefik,mihaitodor/traefik,FriggaHel/traefik,lewisheadden/traefik,SantoDE/traefik,Nitro/traefik,dtomcej/traefik,lewisheadden/traefik,aantono/traefik,akanto/traefik,mildis/traefik,containous/traefik,mihaitodor/traefik,carriercomm/traefik,mvdstam/traefik,CyrilPeponnet/traefik,thomasbach76/traefik,EmileVauge/traefik,ldez/traefik,vdemeester/traefik,owen/traefik,Nitro/traefik,simbas/traefik,mmatur/traefik,marco-jantke/traefik,atbore-phx/traefik,akanto/traefik,tanyadegurechaff/traefik,carriercomm/traefik,mmatur/traefik,atbore-phx/traefik,containous/traefik,FriggaHel/traefik,martinbaillie/traefik,vdemeester/traefik,aantono/traefik,bparli/traefik,simbas/traefik,EmileVauge/traefik,atbore-phx/traefik,adityacs/traefik,mihaitodor/traefik,mvdstam/traefik,adityacs/traefik,yyekhlef/traefik,SantoDE/traefik,Regner/traefik,bparli/traefik,martinbaillie/traefik,FriggaHel/traefik,vholovko/traefik,seryl/traefik,dtomcej/traefik,Nitro/traefik,marco-jantke/traefik,kekoav/traefik,thomasbach76/traefik,vholovko/traefik,kekoav/traefik,mmatur/traefik,timoreimann/traefik,mildis/traefik,carriercomm/traefik,akanto/traefik,aantono/traefik,EmileVauge/traefik,marco-jantke/traefik,seryl/traefik,bparli/traefik,dtomcej/traefik,nmengin/traefik,aantono/traefik,EmileVauge/traefik,Nitro/traefik,Regner/traefik,bparli/traefik,marco-jantke/traefik,timoreimann/traefik,ldez/traefik,kekoav/traefik,jangie/traefik