feat(git): add support to only fetch repositories

add `fetch_only` to config in case user wants to only fetch, not already
pull changes

Closes topgrade-rs#806

config.example.toml

@@ -196,6 +196,8 @@
 # Arguments to pass Git when pulling Repositories
 # arguments = "--rebase --autostash"
 
+# Whether to fetch only instead of pulling remote changes
+# fetch_only = false
 
 [windows]
 # Manually select Windows updates

src/config.rs

@@ -197,6 +197,8 @@ pub struct Git {
     repos: Option<Vec<String>>,
 
     pull_predefined: Option<bool>,
+
+    fetch_only: Option<bool>,
 }
 
 #[derive(Deserialize, Default, Debug, Merge)]
@@ -1050,6 +1052,11 @@ impl Config {
         self.config_file.git.as_ref().and_then(|git| git.arguments.as_ref())
     }
 
+    /// Only fetch repo's instead of pulling
+    pub fn git_fetch_only(&self) -> Option<&bool> {
+        self.config_file.git.as_ref().and_then(|git| git.fetch_only.as_ref())
+    }
+
     pub fn tmux_config(&self) -> Result<TmuxConfig> {
         let args = self.tmux_arguments()?;
         Ok(TmuxConfig {

src/steps/git.rs

@@ -295,16 +295,24 @@ impl RepoStep {
     async fn pull_repo<P: AsRef<Path>>(&self, ctx: &ExecutionContext<'_>, repo: P) -> Result<()> {
         let before_revision = get_head_revision(&self.git, &repo);
 
-        if ctx.config().verbose() {
-            println!("{} {}", style("Pulling").cyan().bold(), repo.as_ref().display());
-        }
-
         let mut command = AsyncCommand::new(&self.git);
 
-        command
-            .stdin(Stdio::null())
-            .current_dir(&repo)
-            .args(["pull", "--ff-only"]);
+        if ctx.config().git_fetch_only().is_some_and(|f| *f) {
+            if ctx.config().verbose() {
+                println!("{} {}", style("Fetching").cyan().bold(), repo.as_ref().display());
+            }
+
+            command.stdin(Stdio::null()).current_dir(&repo).args(["fetch"]);
+        } else {
+            if ctx.config().verbose() {
+                println!("{} {}", style("Pulling").cyan().bold(), repo.as_ref().display());
+            }
+
+            command
+                .stdin(Stdio::null())
+                .current_dir(&repo)
+                .args(["pull", "--ff-only"]);
+        }
 
         if let Some(extra_arguments) = ctx.config().git_arguments() {
             command.args(extra_arguments.split_whitespace());