hardcode epoch so yum-builddep will work

Looks like yum-builddep will only work if rpmlint passed on the spec
file and the spec file errors out on Epoch not being hardcoded.

Signed-off-by: Andrew Hsu <andrewhsu@docker.com>
Upstream-commit: 42b49f6556022ecba47801f4639ddbc7864c9fe0
Component: packaging

components/packaging/rpm/Makefile

@@ -5,10 +5,8 @@ GITCOMMIT=$(shell cd $(ENGINE_DIR) && git rev-parse --short HEAD)
 VERSION?=0.0.0-dev
 GO_VERSION:=1.10.3
 GEN_RPM_VER=$(shell ./gen-rpm-ver $(ENGINE_DIR) $(VERSION))
-EPOCH?=2
 CHOWN=docker run --rm -i -v $(CURDIR):/v -w /v alpine chown
 RPMBUILD=docker run --privileged --rm -i\
-	-e EPOCH="$(EPOCH)" \
 	-v $(CURDIR)/rpmbuild/SOURCES:/root/rpmbuild/SOURCES \
 	-v $(CURDIR)/rpmbuild/BUILD:/root/rpmbuild/BUILD \
 	-v $(CURDIR)/rpmbuild/BUILDROOT:/root/rpmbuild/BUILDROOT \

components/packaging/rpm/centos-7/docker-ce.spec

@@ -1,7 +1,7 @@
 Name: docker-ce
 Version: %{_version}
 Release: %{_release}%{?dist}
-Epoch: %{getenv:EPOCH}
+Epoch: 2
 Summary: The open-source application container engine
 Group: Tools/Docker
 License: ASL 2.0

components/packaging/rpm/fedora-27/docker-ce.spec

@@ -1,7 +1,7 @@
 Name: docker-ce
 Version: %{_version}
 Release: %{_release}%{?dist}
-Epoch: %{getenv:EPOCH}
+Epoch: 2
 Summary: The open-source application container engine
 Group: Tools/Docker
 License: ASL 2.0

components/packaging/rpm/fedora-28/docker-ce.spec

@@ -1,7 +1,7 @@
 Name: docker-ce
 Version: %{_version}
 Release: %{_release}%{?dist}
-Epoch: %{getenv:EPOCH}
+Epoch: 2
 Summary: The open-source application container engine
 Group: Tools/Docker
 License: ASL 2.0