Add ability to clone Git repo branches

Summary:
Unfortunately we can't just use `git.rev` in manifests to specify branches as we clone using `--depth`. This means `rev-parse` on a remote branch name will fail.

This diff adds `git.branch` which allows us to be explicit when we want a branch and so check this out in the first place. By doing this future uses of `rev-parse` will also understand the branch name.

Reviewed By: martindemello

Differential Revision: D79660472

fbshipit-source-id: 6b04158bdd72c28864322be28d88ee4e41f54bc8

Author: jbower-fb

build/fbcode_builder/getdeps/fetcher.py

@@ -218,7 +218,7 @@ def __init__(self) -> None:
 class GitFetcher(Fetcher):
     DEFAULT_DEPTH = 1
 
-    def __init__(self, build_options, manifest, repo_url, rev, depth) -> None:
+    def __init__(self, build_options, manifest, repo_url, rev, depth, branch) -> None:
         # Extract the host/path portions of the URL and generate a flattened
         # directory name.  eg:
         # github.com/facebook/folly.git -> github.com-facebook-folly.git
@@ -249,10 +249,11 @@ def __init__(self, build_options, manifest, repo_url, rev, depth) -> None:
                         "Using pinned rev %s for %s" % (rev, repo_url), file=sys.stderr
                     )
 
-        self.rev = rev or "main"
+        self.rev = rev or branch or "main"
         self.origin_repo = repo_url
         self.manifest = manifest
         self.depth = depth if depth else GitFetcher.DEFAULT_DEPTH
+        self.branch = branch
 
     def _update(self) -> ChangeStatus:
         current_hash = (
@@ -295,17 +296,19 @@ def _clone(self) -> None:
         # eg: this python process is native win32, but the git.exe is cygwin
         # or msys and doesn't like the absolute windows path that we'd otherwise
         # pass to it.  Careful use of cwd helps avoid headaches with cygpath.
-        run_cmd(
-            [
-                "git",
-                "clone",
-                "--depth=" + str(self.depth),
-                "--",
-                self.origin_repo,
-                os.path.basename(self.repo_dir),
-            ],
-            cwd=os.path.dirname(self.repo_dir),
-        )
+        cmd = [
+            "git",
+            "clone",
+            "--depth=" + str(self.depth),
+        ]
+        if self.branch:
+            cmd.append("--branch=" + self.branch)
+        cmd += [
+            "--",
+            self.origin_repo,
+            os.path.basename(self.repo_dir),
+        ]
+        run_cmd(cmd, cwd=os.path.dirname(self.repo_dir))
         self._update()
 
     def clean(self) -> None:

build/fbcode_builder/getdeps/manifest.py

@@ -57,7 +57,12 @@
     "depends.environment": {"optional_section": True},
     "git": {
         "optional_section": True,
-        "fields": {"repo_url": REQUIRED, "rev": OPTIONAL, "depth": OPTIONAL},
+        "fields": {
+            "repo_url": REQUIRED,
+            "rev": OPTIONAL,
+            "depth": OPTIONAL,
+            "branch": OPTIONAL,
+        },
     },
     "download": {
         "optional_section": True,
@@ -461,7 +466,8 @@ def _create_fetcher(self, build_options, ctx):
         if repo_url:
             rev = self.get("git", "rev")
             depth = self.get("git", "depth")
-            return GitFetcher(build_options, self, repo_url, rev, depth)
+            branch = self.get("git", "branch")
+            return GitFetcher(build_options, self, repo_url, rev, depth, branch)
 
         if url:
             # We need to defer this import until now to avoid triggering

build/fbcode_builder/manifests/meta-python-3_12

@@ -8,7 +8,8 @@ shipit_fbcode_builder = false
 shipit_external_branch = meta/3.12
 
 [git]
-repo_url = https://github.com/facebookincubator/cinder.git#meta/3.12
+repo_url = https://github.com/facebookincubator/cinder.git
+branch = meta/3.12
 
 [build]
 builder = autoconf