Reject requests to set the commit flag and trybots on private issues.
Reject requests to set the commit flag and trybots on private issues.

Review URL: https://codereview.appspot.com/110020047/

Koulio/rietveld,sajingeo/rietveld,arg0/rietveld,robfig/rietveld,ericmckean/rietveld,supriyantomaftuh/rietveld,foolonhill/rietveld,andyzsf/rietveld,xtypebee/rietveld,andyzsf/rietveld,salomon1184/rietveld,foolonhill/rietveld,ericmckean/rietveld,draem0507/rietveld,arg0/rietveld,google-code-export/rietveld,Koulio/rietveld,DeanHere/rietveld,draem0507/rietveld,robfig/rietveld,fuzan/rietveld,gavioto/rietveld,gavioto/rietveld,sajingeo/rietveld,xtypebee/rietveld,gco/rietveld,ericmckean/rietveld,aungzanbaw/rietveld,salomon1184/rietveld,aungzanbaw/rietveld,sajingeo/rietveld,openlabs/cr.openlabs.co.in,arg0/rietveld,rietveld-codereview/rietveld,salomon1184/rietveld,gavioto/rietveld,foolonhill/rietveld,google-code-export/rietveld,andyzsf/rietveld,v3ss0n/rietveld,draem0507/rietveld,rietveld-codereview/rietveld,v3ss0n/rietveld,berkus/rietveld,gco/rietveld,DeanHere/rietveld,rietveld-codereview/rietveld,aungzanbaw/rietveld,dushmis/rietveld,fuzan/rietveld,openlabs/cr.openlabs.co.in,rietveld-codereview/rietveld,DeanHere/rietveld,supriyantomaftuh/rietveld,v3ss0n/rietveld,dushmis/rietveld,fuzan/rietveld,dushmis/rietveld,Koulio/rietveld,berkus/rietveld,berkus/rietveld,gco/rietveld,google-code-export/rietveld,supriyantomaftuh/rietveld,robfig/rietveld,openlabs/cr.openlabs.co.in,xtypebee/rietveld