surf: Remove `last_commit` field from `Entry` and `Tree` — radicle-git

Instead of providing the last commit for each Entry and Tree, one should use surf::repo::Repository::last_commit to calculate the last commit of a file where needed.

             .entries(self)?
             .map(|en| {
                 let name = en.name().to_string();
                 let path = en.path();
                 let commit = self
                     .last_commit(&path, commit.id)?
                     .ok_or(error::Repo::PathNotFound(path))?;
                 Ok(Entry::new(name, en.into(), commit))
                 Ok(Entry::new(name, en.into()))
             })
             .collect::<Result<Vec<Entry>, Error>>()?;
         entries.sort();
         let last_commit = self
             .last_commit(path, commit)?
             .ok_or_else(|| error::Repo::PathNotFound(path.as_ref().to_path_buf()))?;
         Ok(Tree::new(dir.id(), entries, last_commit))
         Ok(Tree::new(dir.id(), entries))
     }
     /// Returns a [`Blob`] for `path` in `commit`.

 //! See git [doc](https://git-scm.com/book/en/v2/Git-Internals-Git-Objects) for more details.
 use std::cmp::Ordering;
 use std::path::Path;
 use radicle_git_ext::Oid;
 #[cfg(feature = "serde")]

 };
 use url::Url;
 use crate::{fs, Commit};
 use crate::{fs, repo, Commit, Error, Repository, ToCommit};
 /// Represents a tree object as in git. It is essentially the content of
 /// one directory. Note that multiple directories can have the same content,

     id: Oid,
     /// The first descendant entries for this tree.
     entries: Vec<Entry>,
     /// The commit object that created this tree object.
     commit: Commit,
 }
 impl Tree {
     /// Creates a new tree, ensuring the `entries` are sorted.
     pub(crate) fn new(id: Oid, mut entries: Vec<Entry>, commit: Commit) -> Self {
     pub(crate) fn new(id: Oid, mut entries: Vec<Entry>) -> Self {
         entries.sort();
         Self {
             id,
             entries,
             commit,
         }
         Self { id, entries }
     }
     pub fn object_id(&self) -> Oid {

     }
     /// Returns the commit that created this tree.
     pub fn commit(&self) -> &Commit {
         &self.commit
     pub fn commit<C: ToCommit, P: AsRef<Path>>(
         &self,
         commit: C,
         path: &P,
         repo: &Repository,
     ) -> Result<Commit, Error> {
         let commit = commit
             .to_commit(repo)
             .map_err(|e| Error::ToCommit(e.into()))?;
         repo.last_commit(path, commit.id)?
             .ok_or(repo::error::Repo::PathNotFound(path.as_ref().to_path_buf()))
             .map_err(Into::into)
     }
     /// Returns the entries of the tree.

         let mut state = serializer.serialize_struct("Tree", FIELDS)?;
         state.serialize_field("oid", &self.id)?;
         state.serialize_field("entries", &self.entries)?;
         state.serialize_field("lastCommit", &self.commit)?;
         state.end()
     }
 }

 pub struct Entry {
     name: String,
     entry: EntryKind,
     /// The commit object that created this entry object.
     commit: Commit,
 }
 impl Entry {
     pub(crate) fn new(name: String, entry: EntryKind, commit: Commit) -> Self {
         Self {
             name,
             entry,
             commit,
         }
     pub(crate) fn new(name: String, entry: EntryKind) -> Self {
         Self { name, entry }
     }
     pub fn name(&self) -> &str {

       "entries": [
         {
           "kind": "blob",
           "lastCommit": {
             "author": {
               "email": "fintan.halpenny@gmail.com",
               "name": "Fintan Halpenny",
               "time": 1578309972
             },
             "committer": {
               "email": "noreply@github.com",
               "name": "GitHub",
               "time": 1578309972
             },
             "description": "I want to have files under src that have separate commits.\r\nThat way src's latest commit isn't the same as all its files, instead it's the file that was touched last.",
             "id": "3873745c8f6ffb45c990eb23b491d4b4b6182f95",
             "message": "Extend the docs (#2)\n\nI want to have files under src that have separate commits.\r\nThat way src's latest commit isn't the same as all its files, instead it's the file that was touched last.",
             "parents": ["d6880352fc7fda8f521ae9b7357668b17bb5bad5"],
             "summary": "Extend the docs (#2)"
           },
           "name": "Eval.hs",
           "oid": "7d6240123a8d8ea8a8376610168a0a4bcb96afd0"
         },
         {
           "kind": "blob",
           "lastCommit": {
             "author": {
               "email": "rudolfs@osins.org",
               "name": "Rūdolfs Ošiņš",
               "time": 1575283266
             },
             "committer": {
               "email": "rudolfs@osins.org",
               "name": "Rūdolfs Ošiņš",
               "time": 1575283266
             },
             "description": "",
             "id": "e24124b7538658220b5aaf3b6ef53758f0a106dc",
             "message": "Move examples to \"src\"\n",
             "parents": ["19bec071db6474af89c866a1bd0e4b1ff76e2b97"],
             "summary": "Move examples to \"src\""
           },
           "name": "memory.rs",
           "oid": "b84992d24be67536837f5ab45a943f1b3f501878"
         }
       ],
       "lastCommit": {
         "author": {
           "email": "rudolfs@osins.org",
           "name": "Rūdolfs Ošiņš",
           "time": 1582198877
         },
         "committer": {
           "email": "noreply@github.com",
           "name": "GitHub",
           "time": 1582198877
         },
         "description": "It was a bad idea to have an actual source file which is used by\r\nradicle-upstream in the fixtures repository. It gets in the way of\r\nlinting and editors pick it up as a regular source file by accident.",
         "id": "a57846bbc8ced6587bf8329fc4bce970eb7b757e",
         "message": "Remove src/Folder.svelte (#3)\n\nIt was a bad idea to have an actual source file which is used by\r\nradicle-upstream in the fixtures repository. It gets in the way of\r\nlinting and editors pick it up as a regular source file by accident.",
         "parents": ["3873745c8f6ffb45c990eb23b491d4b4b6182f95"],
         "summary": "Remove src/Folder.svelte (#3)"
       },
       "oid": "ed52e9f8dfe1d8b374b2a118c25235349a743dd2"
     });
     assert_eq!(serde_json::to_value(tree).unwrap(), expected)

     // Verify the last commit is the empty commit.
     assert_eq!(
         tree.commit().id.to_string(),
         "e972683fe8136bf8a5cb2378cf50303554008049"
     );
         tree.object_id().to_string(),
         "4b825dc642cb6eb9a060e54bf8d69288fbee4904"
     )
 }
 #[test]

         .unwrap();
     assert_eq!(tree.entries().len(), 3);
     let commit_header = tree.commit();
     assert_eq!(
         commit_header.id.to_string(),
         "e24124b7538658220b5aaf3b6ef53758f0a106dc"
     );
     let tree_oid = tree.object_id();
     assert_eq!(
         tree_oid.to_string(),

         entry.object_id().to_string(),
         "8c7447d13b907aa994ac3a38317c1e9633bf0732"
     );
     let commit = entry.commit();
     assert_eq!(
         commit.id.to_string(),
         "e24124b7538658220b5aaf3b6ef53758f0a106dc"
     );
     // Verify that an empty path works for getting the root tree.
     let root_tree = repo