revisionstore: remove into_boxed_slice usage

Summary:
I learned that Box::from() can be used to copy a slice into a box, so
let's replace my previous to_vec().into_boxed_slice() with this.

Reviewed By: quark-zju

Differential Revision: D9350961

fbshipit-source-id: 94053b82cd64923dfabc9acf3a9dab6daca20cf3

lib/revisionstore/src/datapack.rs

@@ -402,7 +402,7 @@ impl<'a> Iterator for DataPackIterator<'a> {
         Some(match entry {
             Ok(ref e) => {
                 self.offset = e.next_offset;
-                Ok(Key::new(e.filename.to_vec().into_boxed_slice(), e.node))
+                Ok(Key::new(Box::from(e.filename), e.node))
             }
             Err(e) => Err(e),
         })

lib/revisionstore/src/mutablehistorypack.rs

@@ -45,7 +45,7 @@ impl MutableHistoryPack {
         // To get the inner map, then insert our new NodeInfo. Unfortunately it requires
         // key.name().clone() though. So we have to do it the long way to avoid the allocation.
         let entries = self.mem_index
-            .entry(key.name().to_vec().into_boxed_slice())
+            .entry(Box::from(key.name()))
             .or_insert_with(|| HashMap::new());
         entries.insert(key.clone(), info.clone());
         Ok(())