Fix error message when installing musl python on armv7 (#17213)

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## Summary

Fixes #17210.

## Test Plan

Added a test function.

Co-authored-by: Zanie Blue <contact@zanie.dev>

crates/uv/src/commands/python/install.rs

@@ -69,12 +69,12 @@ impl<'a> InstallRequest<'a> {
             Ok(download) => download,
             Err(downloads::Error::NoDownloadFound(request))
                 if request.libc().is_some_and(Libc::is_musl)
-                    && request
-                        .arch()
-                        .is_some_and(|arch| Arch::is_arm(&arch.inner())) =>
+                    && request.arch().is_some_and(|arch| {
+                        arch.inner() == Arch::from(&uv_platform_tags::Arch::Armv7L)
+                    }) =>
             {
                 return Err(anyhow::anyhow!(
-                    "uv does not yet provide musl Python distributions on aarch64."
+                    "uv does not yet provide musl Python distributions on armv7."
                 ));
             }
             Err(err) => return Err(err.into()),

crates/uv/tests/it/python_install.rs

@@ -3954,6 +3954,39 @@ fn python_install_upgrade_version_file() {
     ");
 }
 
+#[test]
+fn python_install_armv7() {
+    let context: TestContext = TestContext::new_with_versions(&[])
+        .with_filtered_python_keys()
+        .with_managed_python_dirs()
+        .with_python_download_cache()
+        .with_filtered_python_sources()
+        .with_filtered_python_install_bin()
+        .with_filtered_python_names()
+        .with_filtered_exe_suffix();
+
+    // Explicitly request a musl build for armv7l
+    uv_snapshot!(context.filters(), context.python_install().arg("cpython-3.12.12-linux-armv7-musl"), @r###"
+    success: false
+    exit_code: 2
+    ----- stdout -----
+
+    ----- stderr -----
+    error: uv does not yet provide musl Python distributions on armv7.
+    "###);
+
+    // Explicitly request a gnuabi build for armv7l
+    uv_snapshot!(context.filters(), context.python_install().arg("cpython-3.12.12-linux-armv7-gnueabi"), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Installed Python 3.12.12 in [TIME]
+     + cpython-3.12.12-[PLATFORM] (python3.12)
+    "###);
+}
+
 #[test]
 fn python_install_compile_bytecode() -> anyhow::Result<()> {
     fn count_files_by_ext(dir: &Path, extension: &str) -> anyhow::Result<usize> {