Retrieve commit ref correctly.

The command `frizbee actions <action>@<tag>` incorrectly retrieves the
tag's ref rather than the commit's one. The tag's ref should instead
be used to retrieve the details of the tag, which contain the ref of
the commit.

This change changes `getCheckSumForTag` to lookup the right field
using two subsequent call to GitHub.

Fixes #206

pkg/replacer/actions/actions.go

@@ -314,7 +314,23 @@ func getCheckSumForTag(ctx context.Context, restIf interfaces.REST, owner, repo,
 		return "", fmt.Errorf("failed to join path: %w", err)
 	}
 
-	return doGetReference(ctx, restIf, path)
+	sha, otype, err := doGetReference(ctx, restIf, path)
+	if err != nil {
+		return "", err
+	}
+
+	if otype == "commit" {
+		return sha, nil
+	}
+
+	// assume otype == "tag"
+	path, err = url.JoinPath("repos", owner, repo, "git", "tags", sha)
+	if err != nil {
+		return "", fmt.Errorf("failed to join path: %w", err)
+	}
+
+	sha, _, err = doGetReference(ctx, restIf, path)
+	return sha, err
 }
 
 func getCheckSumForBranch(ctx context.Context, restIf interfaces.REST, owner, repo, branch string) (string, error) {
@@ -323,7 +339,8 @@ func getCheckSumForBranch(ctx context.Context, restIf interfaces.REST, owner, re
 		return "", fmt.Errorf("failed to join path: %w", err)
 	}
 
-	return doGetReference(ctx, restIf, path)
+	sha, _, err := doGetReference(ctx, restIf, path)
+	return sha, err
 }
 
 func excludeBranch(excludes []string, branch string) bool {
@@ -337,10 +354,10 @@ func excludeBranch(excludes []string, branch string) bool {
 	return slices.Contains(excludes, branch)
 }
 
-func doGetReference(ctx context.Context, restIf interfaces.REST, path string) (string, error) {
+func doGetReference(ctx context.Context, restIf interfaces.REST, path string) (string, string, error) {
 	req, err := restIf.NewRequest(http.MethodGet, path, nil)
 	if err != nil {
-		return "", fmt.Errorf("cannot create REST request: %w", err)
+		return "", "", fmt.Errorf("cannot create REST request: %w", err)
 	}
 
 	resp, err := restIf.Do(ctx, req)
@@ -352,20 +369,20 @@ func doGetReference(ctx context.Context, restIf interfaces.REST, path string) (s
 	}
 
 	if err != nil && resp.StatusCode != http.StatusNotFound {
-		return "", fmt.Errorf("failed to do API request: %w", err)
+		return "", "", fmt.Errorf("failed to do API request: %w", err)
 	} else if resp.StatusCode == http.StatusNotFound {
 		// No error, but no tag found
-		return "", nil
+		return "", "", nil
 	}
 
 	var t github.Reference
 	err = json.NewDecoder(resp.Body).Decode(&t)
 	if err != nil && strings.Contains(err.Error(), "cannot unmarshal array into Go value of type") {
 		// This is a branch, not a tag
-		return "", nil
+		return "", "", nil
 	} else if err != nil {
-		return "", fmt.Errorf("canont decode response: %w", err)
+		return "", "", fmt.Errorf("canont decode response: %w", err)
 	}
 
-	return t.GetObject().GetSHA(), nil
+	return t.GetObject().GetSHA(), t.GetObject().GetType(), nil
 }

pkg/replacer/replacer_test.go

@@ -792,7 +792,7 @@ jobs:
     steps:
       - uses: ./minder/server.yml # this should not be replaced
       - uses: actions/checkout@ee0669bd1cc54295c223e0bb666b733df41de1c5 # v2
-      - uses: xt0rted/markdownlint-problem-matcher@c17ca40d1376f60aba7e7d38a8674a3f22f7f5b0 # v1
+      - uses: xt0rted/markdownlint-problem-matcher@b643b0751c371f357690337d4549221347c0e1bc # v1
       - name: "Run Markdown linter"
         uses: docker://index.docker.io/avtodev/markdown-lint@sha256:6aeedc2f49138ce7a1cd0adffc1b1c0321b841dc2102408967d9301c031949ee # v1
         with:
@@ -905,7 +905,7 @@ jobs:
     steps:
       - uses: ./minder/server.yml # this should not be replaced
       - uses: actions/checkout@ee0669bd1cc54295c223e0bb666b733df41de1c5 # v2
-      - uses: xt0rted/markdownlint-problem-matcher@c17ca40d1376f60aba7e7d38a8674a3f22f7f5b0 # v1
+      - uses: xt0rted/markdownlint-problem-matcher@b643b0751c371f357690337d4549221347c0e1bc # v1
 `,
 			modified: true,
 		},
@@ -1398,7 +1398,7 @@ jobs:
 		   steps:
 		     - uses: ./minder/server.yml # this should not be replaced
 		     - uses: actions/checkout@ee0669bd1cc54295c223e0bb666b733df41de1c5 # v2
-		     - uses: xt0rted/markdownlint-problem-matcher@c17ca40d1376f60aba7e7d38a8674a3f22f7f5b0 # v1
+		     - uses: xt0rted/markdownlint-problem-matcher@b643b0751c371f357690337d4549221347c0e1bc # v1
 		`,
 			expected: &ListResult{
 				Entities: []interfaces.EntityRef{
@@ -1409,7 +1409,7 @@ jobs:
 					},
 					{
 						Name: "xt0rted/markdownlint-problem-matcher",
-						Ref:  "c17ca40d1376f60aba7e7d38a8674a3f22f7f5b0",
+						Ref:  "b643b0751c371f357690337d4549221347c0e1bc",
 						Type: actions.ReferenceType,
 					},
 				},