changelog: allow writing changelog in a non-git package

src/changelog.rs

@@ -19,26 +19,22 @@ pub fn generate_entry(
         Path::new(changelog_file).to_path_buf()
     };
 
-    // 1. Parse existing changelog to get current (old) version
+    // Parse existing changelog to get current (old) version
     let (package, old_version, series) = parse_changelog_header(&changelog_path)?;
     println!("Found package: {}, version: {}", package, old_version);
 
-    // 2. Open git repo
+    // Open git repo, and find commits since last version tag
     let repo_path = if let Some(path) = cwd {
         path.to_path_buf()
     } else {
         std::env::current_dir()?
     };
-    let repo = Repository::open(&repo_path)?;
-
-    // 3. Find commits since the tag corresponding to the version
-
-    let commits = get_commits_since_version(&repo, &old_version)?;
-
-    if commits.is_empty() {
-        println!("No new commits found since version {}", old_version);
-        // return Ok(());
-    }
+    let commits = match Repository::open(&repo_path) {
+        Ok(repo) => get_commits_since_version(&repo, &old_version)?,
+        // If there is no git repo (e.g. package downloaded from archive),
+        // we just generate an empty list of changes
+        Err(_e) => Vec::new(),
+    };
 
     // Compute new version if needed, or use user-supplied one
     let new_version = if let Some(version) = user_version {