Include committer date in local version identifier of unstable builds (…

…pantsbuild#19179)

Fixes pantsbuild#7399 by adjusting the local version identifier of 'unstable'
wheels to also include a timestamp, so that builds with the same stable
version can be sorted in a vaguely sensible way, without having to
dereference the git hash manually.

The timestamp chosen is the committer date of the commit in question,
formatted as a vaguely human readable number (`yyyymmddHHMM`). For
example, this PR's CI built
`pantsbuild.pants-2.18.0.dev0+202305302357.git111f44db-cp39-cp39-macosx_11_0_arm64.whl`,
corresponding to 2023-05-30 23:57.

build-support/bin/release.py

@@ -389,6 +389,22 @@ def __init__(self) -> None:
             .stdout.decode()
             .strip()
         )
+        self._head_committer_date = (
+            subprocess.run(
+                [
+                    "git",
+                    "show",
+                    "--no-patch",
+                    "--format=%cd",
+                    "--date=format:%Y%m%d%H%M",
+                    self._head_sha,
+                ],
+                stdout=subprocess.PIPE,
+                check=True,
+            )
+            .stdout.decode()
+            .strip()
+        )
         self.pants_version_file = Path("src/python/pants/VERSION")
         self.pants_stable_version = self.pants_version_file.read_text().strip()
 
@@ -418,7 +434,9 @@ def deploy_pants_wheel_dir(self) -> Path:
 
     @property
     def pants_unstable_version(self) -> str:
-        return f"{self.pants_stable_version}+git{self._head_sha[:8]}"
+        # include the commit's timestamp to make multiple builds of a single stable version more
+        # easily orderable
+        return f"{self.pants_stable_version}+{self._head_committer_date}.git{self._head_sha[:8]}"
 
     @property
     def twine_venv_dir(self) -> Path: