Enable using cache registry for the first build

Registry caching was disabled for the first build although it permits
to share cache between images. This will speed lot of first builds.

pkg/apis/build/v1alpha2/build_pod.go

@@ -269,6 +269,8 @@ func (b *Build) BuildPod(images BuildPodImages, buildContext BuildContext) (*cor
 		useCacheFromLastBuild := b.Spec.LastBuild != nil && b.Spec.LastBuild.Cache.Image != ""
 		if useCacheFromLastBuild {
 			genericCacheArgs = []string{fmt.Sprintf("-cache-image=%s", b.Spec.LastBuild.Cache.Image)}
+		} else {
+			genericCacheArgs = []string{fmt.Sprintf("-cache-image=%s", b.Spec.Cache.Registry.Tag)}
 		}
 		analyzerCacheArgs = genericCacheArgs
 		exporterCacheArgs = []string{fmt.Sprintf("-cache-image=%s", b.Spec.Cache.Registry.Tag)}

pkg/apis/build/v1alpha2/build_pod_test.go

@@ -1053,19 +1053,19 @@ func testBuildPod(t *testing.T, when spec.G, it spec.S) {
 					assert.Len(t, podWithImageCache.Spec.Volumes, len(podWithVolumeCache.Spec.Volumes)-1)
 				})
 
-				it("does not add the cache to analyze container", func() {
+				it("does add the cache to analyze container", func() {
 					podWithImageCache, err := build.BuildPod(config, buildContext)
 					require.NoError(t, err)
 
 					analyzeContainer := podWithImageCache.Spec.InitContainers[2]
-					assert.NotContains(t, analyzeContainer.Args, "-cache-image=test-cache-image")
+					assert.Contains(t, analyzeContainer.Args, "-cache-image=test-cache-image")
 				})
-				it("does not add the cache to restore container", func() {
+				it("does add cache to restore container", func() {
 					podWithImageCache, err := build.BuildPod(config, buildContext)
 					require.NoError(t, err)
 
 					restoreContainer := podWithImageCache.Spec.InitContainers[3]
-					assert.NotContains(t, restoreContainer.Args, "-cache-image=test-cache-image")
+					assert.Contains(t, restoreContainer.Args, "-cache-image=test-cache-image")
 				})
 				it("adds the cache to export container", func() {
 					podWithImageCache, err := build.BuildPod(config, buildContext)