feat: display the underlying permission denied error as source when f…

…ailng handshake due to authentication.

git-protocol/src/handshake/function.rs

@@ -58,7 +58,7 @@ where
                     // Still no permission? Reject the credentials.
                     Err(client::Error::Io(err)) if err.kind() == std::io::ErrorKind::PermissionDenied => {
                         authenticate(next.erase())?;
-                        return Err(Error::InvalidCredentials { url });
+                        return Err(Error::InvalidCredentials { url, source: err });
                     }
                     // Otherwise, do nothing, as we don't know if it actually got to try the credentials.
                     // If they were previously stored, they remain. In the worst case, the user has to enter them again

git-protocol/src/handshake/mod.rs

@@ -69,7 +69,7 @@ mod error {
         #[error("Failed to obtain credentials")]
         Credentials(#[from] credentials::protocol::Error),
         #[error("Credentials provided for \"{url}\" were not accepted by the remote")]
-        InvalidCredentials { url: BString },
+        InvalidCredentials { url: BString, source: std::io::Error },
         #[error(transparent)]
         Transport(#[from] client::Error),
         #[error("The transport didn't accept the advertised server version {actual_version:?} and closed the connection client side")]