erepo: drop dvcx for_write support

dvc/repo/open_repo.py

@@ -23,11 +23,10 @@ logger = logging.getLogger(__name__)
 def _external_repo(
     url,
     rev: Optional[str] = None,
-    for_write: bool = False,
     **kwargs,
 ) -> Iterator["Repo"]:
     logger.debug("Creating external repo %s@%s", url, rev)
-    path = _cached_clone(url, rev, for_write=for_write)
+    path = _cached_clone(url, rev)
     # Local HEAD points to the tip of whatever branch we first cloned from
     # (which may not be the default branch), use origin/HEAD here to get
     # the tip of the default branch
@@ -38,11 +37,6 @@ def _external_repo(
     config.update(kwargs.pop("config", None) or {})
 
     main_root = "/"
-    if for_write:
-        # we already checked out needed revision
-        rev = None
-        main_root = path
-
     repo_kwargs = dict(
         root_dir=path,
         url=url,
@@ -58,8 +52,6 @@ def _external_repo(
         yield repo
     finally:
         repo.close()
-        if for_write:
-            _remove(path)
 
 
 def open_repo(url, *args, **kwargs):
@@ -140,20 +132,19 @@ def _get_remote_config(url):
         repo.close()
 
 
-def _cached_clone(url, rev, for_write=False):
+def _cached_clone(url, rev):
     """Clone an external git repo to a temporary directory.
 
     Returns the path to a local temporary directory with the specified
-    revision checked out. If for_write is set prevents reusing this dir via
-    cache.
+    revision checked out.
     """
     from shutil import copytree
 
     # even if we have already cloned this repo, we may need to
     # fetch/fast-forward to get specified rev
-    clone_path, shallow = _clone_default_branch(url, rev, for_write=for_write)
+    clone_path, shallow = _clone_default_branch(url, rev)
 
-    if not for_write and (url) in CLONES:
+    if url in CLONES:
         return CLONES[url][0]
 
     # Copy to a new dir to keep the clone clean
@@ -161,16 +152,12 @@ def _cached_clone(url, rev, for_write=False):
     logger.debug("erepo: making a copy of %s clone", url)
     copytree(clone_path, repo_path)
 
-    # Check out the specified revision
-    if for_write:
-        _git_checkout(repo_path, rev)
-    else:
-        CLONES[url] = (repo_path, shallow)
+    CLONES[url] = (repo_path, shallow)
     return repo_path
 
 
 @wrap_with(threading.Lock())
-def _clone_default_branch(url, rev, for_write=False):  # noqa: C901, PLR0912
+def _clone_default_branch(url, rev):  # noqa: C901, PLR0912
     """Get or create a clean clone of the url.
 
     The cloned is reactualized with git pull unless rev is a known sha.
@@ -204,7 +191,7 @@ def _clone_default_branch(url, rev, for_write=False):  # noqa: C901, PLR0912
 
             logger.debug("erepo: git clone '%s' to a temporary dir", url)
             clone_path = tempfile.mkdtemp("dvc-clone")
-            if not for_write and rev and not Git.is_sha(rev):
+            if rev and not Git.is_sha(rev):
                 # If rev is a tag or branch name try shallow clone first
 
                 try:
@@ -249,17 +236,6 @@ def _merge_upstream(git: "Git"):
         pass
 
 
-def _git_checkout(repo_path, rev):
-    from dvc.scm import Git
-
-    logger.debug("erepo: git checkout %s@%s", repo_path, rev)
-    git = Git(repo_path)
-    try:
-        git.checkout(rev)
-    finally:
-        git.close()
-
-
 def _remove(path):
     from dvc.utils.fs import remove