disk: resolve iter_nth_zero clippy warning

Replace .nth(0) with .next() to resolve this:

  error: called `.nth(0)` on a `std::iter::Iterator`

BUG=None
TEST=bin/clippy

Change-Id: I103e8b44b1564708d92d096aaf044db7f67d1ba8
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/2151147
Reviewed-by: Zach Reizner <zachr@chromium.org>
Tested-by: Daniel Verkamp <dverkamp@chromium.org>
Commit-Queue: Keiichi Watanabe <keiichiw@chromium.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/disk/src/qcow/vec_cache.rs b/disk/src/qcow/vec_cache.rs
index ecd7673..18cfc69 100644
--- a/disk/src/qcow/vec_cache.rs
+++ b/disk/src/qcow/vec_cache.rs
@@ -120,7 +120,7 @@ impl<T: Cacheable> CacheMap<T> {
     {
         if self.map.len() == self.capacity {
             // TODO(dgreid) - smarter eviction strategy.
-            let to_evict = *self.map.iter().nth(0).unwrap().0;
+            let to_evict = *self.map.iter().next().unwrap().0;
             if let Some(evicted) = self.map.remove(&to_evict) {
                 if evicted.dirty() {
                     write_callback(to_evict, evicted)?;