rust-revlog: change default version from 2 to 1 in test builder

Version 1 is the only version we support, so it seems like the natural
choice for making it easy to create valid revlogs.

Differential Revision: https://phab.mercurial-scm.org/D12563

rust/hg-core/src/revlog/index.rs

@@ -323,7 +323,7 b' mod tests {'
                 is_first: false,
                 is_inline: false,
                 is_general_delta: true,
-                version: 2,
+                version: 1,
                 offset: 0,
                 compressed_len: 0,
                 uncompressed_len: 0,
@@ -517,10 +517,10 b' mod tests {'
     fn version_test() {
         let bytes = IndexEntryBuilder::new()
             .is_first(true)
-            .with_version(1)
+            .with_version(2)
             .build();
 
-        assert_eq!(get_version(&bytes), 1)
+        assert_eq!(get_version(&bytes), 2)
     }
 }