re-add kodata symlink tests for linux

.github/workflows/e2e.yaml

@@ -41,4 +41,11 @@ jobs:
         docker run $(go run ./ publish ./ --platform=${GOOS}/${GOARCH} --preserve-import-paths) version
 
         # Build and run the test/ binary, which should log "Hello there" served from KO_DATA_PATH
-        docker run $(go run ./ publish ./test --platform=${GOOS}/${GOARCH} --preserve-import-paths) --wait=false 2>&1 | grep "Hello there"
+        testimg=$(go run ./ publish ./test --platform=${GOOS}/${GOARCH} --preserve-import-paths)
+        docker run ${testimg} --wait=false 2>&1 | grep "Hello there"
+
+        # Check that symlinks in kodata are chased.
+        # Skip this test on Windows.
+        if [[ "$RUNNER_OS" == "Linux" ]]; then
+          docker run ${testimg} --wait=false -f HEAD
+        fi

test/kodata/HEAD

@@ -0,0 +1 @@
+../../.git/HEAD

test/kodata/refs

@@ -0,0 +1 @@
+../../.git/refs

test/main.go

@@ -25,14 +25,15 @@ import (
 )
 
 var (
+	f    = flag.String("f", "kenobi", "File in kodata to print")
 	wait = flag.Bool("wait", true, "Whether to wait for SIGTERM")
 )
 
 func main() {
 	flag.Parse()
 
 	dp := os.Getenv("KO_DATA_PATH")
-	file := filepath.Join(dp, "kenobi")
+	file := filepath.Join(dp, *f)
 	bytes, err := ioutil.ReadFile(file)
 	if err != nil {
 		log.Fatalf("Error reading %q: %v", file, err)