Track retry counts originating from early middleware errors (#17274)

## Summary

Fixes #17266.

The retry count was getting dropped by
`ErrorKind::from_retry_middleware` and `<Error as
From<ErrorKind>>::from` so we were doing more retries than we should
have.

## Test Plan

Added a testcase for the specific error path in the issue. Added an
expect to the other retry test too.

crates/uv-client/src/error.rs

@@ -246,9 +246,15 @@ impl Error {
 
 impl From<ErrorKind> for Error {
     fn from(kind: ErrorKind) -> Self {
-        Self {
-            kind: Box::new(kind),
-            retries: 0,
+        match kind {
+            ErrorKind::RequestWithRetries { source, retries } => Self {
+                kind: source,
+                retries,
+            },
+            other => Self {
+                kind: Box::new(other),
+                retries: 0,
+            },
         }
     }
 }
@@ -391,6 +397,18 @@ impl ErrorKind {
             if let Some(err) = underlying.downcast_ref::<OfflineError>() {
                 return Self::Offline(err.url().to_string());
             }
+            if let Some(reqwest_retry::RetryError::WithRetries { retries, .. }) =
+                underlying.downcast_ref::<reqwest_retry::RetryError>()
+            {
+                let retries = *retries;
+                return Self::RequestWithRetries {
+                    source: Box::new(Self::WrappedReqwestError(
+                        url,
+                        WrappedReqwestError::from(err),
+                    )),
+                    retries,
+                };
+            }
         }
 
         Self::WrappedReqwestError(url, WrappedReqwestError::from(err))

crates/uv/tests/it/network.rs

@@ -5,7 +5,7 @@ use http::StatusCode;
 use serde_json::json;
 use uv_static::EnvVars;
 use wiremock::matchers::method;
-use wiremock::{Mock, MockServer, ResponseTemplate};
+use wiremock::{Mock, MockServer, Request, ResponseTemplate};
 
 use crate::common::{TestContext, uv_snapshot};
 
@@ -392,6 +392,7 @@ async fn install_http_retries() {
     // Create a server that always fails, so we can see the number of retries used
     Mock::given(method("GET"))
         .respond_with(ResponseTemplate::new(503))
+        .expect(6)
         .mount(&server)
         .await;
 
@@ -455,6 +456,40 @@ async fn install_http_retries() {
     );
 }
 
+#[tokio::test]
+async fn install_http_retry_low_level() {
+    let context = TestContext::new("3.12");
+
+    let server = MockServer::start().await;
+
+    // Create a server that fails with a more fundamental error so we trigger
+    // earlier error paths
+    Mock::given(method("GET"))
+        .respond_with_err(|_: &'_ Request| io::Error::new(io::ErrorKind::ConnectionReset, "error"))
+        .expect(2)
+        .mount(&server)
+        .await;
+
+    uv_snapshot!(context.filters(), context.pip_install()
+        .arg("anyio")
+        .arg("--index")
+        .arg(server.uri())
+        .env(EnvVars::UV_HTTP_RETRIES, "1")
+        .env(EnvVars::UV_TEST_NO_HTTP_RETRY_DELAY, "true"), @r"
+    success: false
+    exit_code: 2
+    ----- stdout -----
+
+    ----- stderr -----
+    error: Request failed after 1 retry
+      Caused by: Failed to fetch: `http://[LOCALHOST]/anyio/`
+      Caused by: error sending request for url (http://[LOCALHOST]/anyio/)
+      Caused by: client error (SendRequest)
+      Caused by: connection closed before message completed
+    "
+    );
+}
+
 /// Test problem details with a 403 error containing license compliance information
 #[tokio::test]
 async fn rfc9457_problem_details_license_violation() {