Bug 1201863: remove variables not used in checkout-sources.sh; r=mrrrgn

--HG--
extra : commitid : KYJph6r4j5h
extra : rebase_source : 5ed82d1613e952e1b0c925723675f4170519cc80
extra : histedit_source : 672a42b4635675f34c0f9181156f349ce9c38ca1

testing/docker/desktop-build/bin/checkout-sources.sh

@@ -25,10 +25,6 @@ set -x -e
 : TOOLS_HEAD_REF                ${TOOLS_HEAD_REF:=${TOOLS_HEAD_REV}}
 : TOOLS_DISABLE                 ${TOOLS_DISABLE:=false}
 
-: MH_CUSTOM_BUILD_VARIANT_CFG   ${MH_CUSTOM_BUILD_VARIANT_CFG}
-: MH_BRANCH                     ${MH_BRANCH:=mozilla-central}
-: MH_BUILD_POOL                 ${MH_BUILD_POOL:=staging}
-
 : WORKSPACE                     ${WORKSPACE:=/home/worker/workspace}
 
 set -v