Avoid spurious 'Upgraded tool environment' in `uv tool upgrade` (#9870)

## Summary

Closes https://github.com/astral-sh/uv/issues/9869.

crates/uv/src/commands/tool/upgrade.rs

@@ -178,17 +178,19 @@ pub(crate) async fn upgrade(
     }
 
     if let Some(python_request) = python_request {
-        let tools = did_upgrade_environment
+        if !did_upgrade_environment.is_empty() {
-            .iter()
+            let tools = did_upgrade_environment
-            .map(|name| format!("`{}`", name.cyan()))
+                .iter()
-            .collect::<Vec<_>>();
+                .map(|name| format!("`{}`", name.cyan()))
-        let s = if tools.len() > 1 { "s" } else { "" };
+                .collect::<Vec<_>>();
-        writeln!(
+            let s = if tools.len() > 1 { "s" } else { "" };
-            printer.stderr(),
+            writeln!(
-            "Upgraded tool environment{s} for {} to {}",
+                printer.stderr(),
-            conjunction(tools),
+                "Upgraded tool environment{s} for {} to {}",
-            python_request.cyan(),
+                conjunction(tools),
-        )?;
+                python_request.cyan(),
+            )?;
+        }
     }
 
     Ok(ExitStatus::Success)

crates/uv/tests/it/tool_upgrade.rs

@@ -5,6 +5,91 @@ use uv_static::EnvVars;
 
 use crate::common::{uv_snapshot, TestContext};
 
+#[test]
+fn tool_upgrade_empty() {
+    let context = TestContext::new("3.12")
+        .with_filtered_counts()
+        .with_filtered_exe_suffix();
+    let tool_dir = context.temp_dir.child("tools");
+    let bin_dir = context.temp_dir.child("bin");
+
+    uv_snapshot!(context.filters(), context.tool_upgrade()
+        .arg("--all")
+        .env(EnvVars::UV_TOOL_DIR, tool_dir.as_os_str())
+        .env(EnvVars::XDG_BIN_HOME, bin_dir.as_os_str())
+        .env(EnvVars::PATH, bin_dir.as_os_str()), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Nothing to upgrade
+    "###);
+
+    uv_snapshot!(context.filters(), context.tool_upgrade()
+        .arg("--all")
+        .arg("-p")
+        .arg("3.13")
+        .env(EnvVars::UV_TOOL_DIR, tool_dir.as_os_str())
+        .env(EnvVars::XDG_BIN_HOME, bin_dir.as_os_str())
+        .env(EnvVars::PATH, bin_dir.as_os_str()), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Nothing to upgrade
+    "###);
+
+    // Install the latest `babel`.
+    uv_snapshot!(context.filters(), context.tool_install()
+        .arg("babel")
+        .arg("--index-url")
+        .arg("https://pypi.org/simple/")
+        .env(EnvVars::UV_TOOL_DIR, tool_dir.as_os_str())
+        .env(EnvVars::XDG_BIN_HOME, bin_dir.as_os_str())
+        .env(EnvVars::PATH, bin_dir.as_os_str()), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Resolved [N] packages in [TIME]
+    Prepared [N] packages in [TIME]
+    Installed [N] packages in [TIME]
+     + babel==2.14.0
+    Installed 1 executable: pybabel
+    "###);
+
+    uv_snapshot!(context.filters(), context.tool_upgrade()
+        .arg("--all")
+        .env(EnvVars::UV_TOOL_DIR, tool_dir.as_os_str())
+        .env(EnvVars::XDG_BIN_HOME, bin_dir.as_os_str())
+        .env(EnvVars::PATH, bin_dir.as_os_str()), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Nothing to upgrade
+    "###);
+
+    uv_snapshot!(context.filters(), context.tool_upgrade()
+        .arg("--all")
+        .arg("-p")
+        .arg("3.12")
+        .env(EnvVars::UV_TOOL_DIR, tool_dir.as_os_str())
+        .env(EnvVars::XDG_BIN_HOME, bin_dir.as_os_str())
+        .env(EnvVars::PATH, bin_dir.as_os_str()), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Nothing to upgrade
+    "###);
+}
+
 #[test]
 fn tool_upgrade_name() {
     let context = TestContext::new("3.12")