perf(clone): clone faster without blobs

When git 2.27 or newer is installed, we can add `--filter=blob:none` to avoid getting useless information from the git server. This makes clone much faster if your template has a big history.

Close #450 (it does not exactly fix it, but maybe makes it irrelevant).

CHANGELOG.md

@@ -44,6 +44,7 @@ Summary:
     complicated anyway (warn added to docs).
 -   Changed `--force` to be the same as `--defaults --overwrite`.
 -   Copied files will reflect permissions on the same files in the template.
+-   Copier now uses `git clone --filter=blob:none` when cloning, to be faster.
 
 ### Deprecated
 

README.md

@@ -22,7 +22,7 @@ A library and CLI app for rendering project templates.
 ## Installation
 
 1. Install Python 3.6.1 or newer (3.8 or newer if you're on Windows).
-1. Install Git 2.24 or newer.
+1. Install Git 2.27 or newer.
 1. To use as a CLI app: `pipx install copier`
 1. To use as a library: `pip install copier`
 

copier/vcs.py

@@ -5,6 +5,7 @@
 from pathlib import Path
 
 from packaging import version
+from packaging.version import Version
 from plumbum import TF, ProcessExecutionError, colors, local
 from plumbum.cmd import git
 
@@ -13,6 +14,7 @@
 
 GIT_PREFIX = ("git@", "git://", "git+")
 GIT_POSTFIX = (".git",)
+GIT_VERSION = Version(git("version").split()[-1].replace(".windows", "+windows"))
 REPLACEMENTS = (
     (re.compile(r"^gh:/?(.*\.git)$"), r"https://github.com/\1"),
     (re.compile(r"^gh:/?(.*)$"), r"https://github.com/\1.git"),
@@ -117,7 +119,11 @@ def clone(url: str, ref: OptStr = None) -> str:
             Reference to checkout. For Git repos, defaults to `HEAD`.
     """
     location = tempfile.mkdtemp(prefix=f"{__name__}.clone.")
-    git("clone", "--no-checkout", url, location)
+    _clone = git["clone", "--no-checkout", url, location]
+    # Faster clones if possible
+    if GIT_VERSION >= Version("2.27"):
+        _clone = _clone["--filter=blob:none"]
+    _clone()
     with local.cwd(location):
         git("checkout", ref or "HEAD")
         git("submodule", "update", "--checkout", "--init", "--recursive", "--force")