RunTransaction hangs if the provided function panics

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Reproduction:

package main

import (
	"context"
	"database/sql"
	"fmt"
	"os"

	spannerdriver "github.com/googleapis/go-sql-spanner"
)

func main() {
	ctx := context.Background()

	db, err := sql.Open("spanner", fmt.Sprintf("projects/%s/instances/%s/databases/%s", os.Getenv("PROJECT"), os.Getenv("INSTANCE"), os.Getenv("DATABASE")))
	if err != nil {
		panic(err)
	}

	err = spannerdriver.RunTransaction(ctx, db, &sql.TxOptions{}, func(ctx context.Context, tx *sql.Tx) error {
		fmt.Println("Panicking")
		panic("panic")
	})
	if err != nil {
		panic(err)
	}

	fmt.Println("Done")
}

Expected output:

Panicking
panic: panic

followed by the process exiting.

Actual output:

Panicking

followed by the process hanging indefinitely.

Note that adding a call to tx.Rollback() within the function passed to RunTransaction fixes the hang. It seems that the outstanding transaction is causing the deferred call to conn.Close() within runTransactionWithOptions to hang indefinitely.

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Thank you!