Allow opt-in shallow cloning (GH-744)

Opt-in on ware-win11-arm64; something seems to be going wrong
with the blobless clones on that worker.

Author: zware

master/custom/workers.py

@@ -38,7 +38,8 @@ def __init__(
         parallel_tests=None,
         timeout_factor=1,
         exclude_test_resources=None,
-        downtime=None
+        downtime=None,
+        git_options=None,
     ):
         self.name = name
         self.tags = tags or set()
@@ -48,6 +49,7 @@ def __init__(
         self.timeout_factor = timeout_factor
         self.exclude_test_resources = exclude_test_resources or []
         self.downtime = downtime
+        self.git_options = git_options or {}
 
         worker_settings = settings.workers[name]
         owner = name.split("-")[0]
@@ -310,6 +312,14 @@ def get_workers(settings):
             tags=['windows', 'win11', 'arm64'],
             parallel_tests=8,
             not_branches=['3.10', '3.11', '3.12'],
+            git_options=dict(
+                # Do a full shallow clone for every build
+                mode="full",
+                method="clobber",
+                shallow=True,
+                # Disable the default, if set
+                filters=None,
+            ),
         ),
         cpw(
             name="bcannon-wasi",

master/master.cfg

@@ -204,17 +204,26 @@ for branch in BRANCHES:
 
         source = GitHub(
             repourl=str(settings.git_url),
-            timeout=3600,
             **branch_args,
-            # "git clean -fdx": remove all files which are not tracked by Git,
-            # ignoring the .gitignore rules (ex: remove also ".o" files).
-            mode="full",
-            method="fresh",
-            # Partial (blobless) clone: only fetch commit and tree objects,
-            # blobs are fetched on demand during checkout.
-            filters=["blob:none"],
-            # If fetch fails, wipe and re-clone instead of failing the build.
-            clobberOnFailure=True,
+            **{
+                # defaults
+                **dict(
+                    timeout=3600,
+                    # "git clean -fdx": remove all files which are not tracked
+                    # by Git, ignoring the .gitignore rules (ex: remove also
+                    # ".o" files).
+                    mode="full",
+                    method="fresh",
+                    # Partial (blobless) clone: only fetch commit and tree
+                    # objects, blobs are fetched on demand during checkout.
+                    filters=["blob:none"],
+                    # If fetch fails, wipe and re-clone instead of failing the
+                    # build.
+                    clobberOnFailure=True,
+                ),
+                # worker-specific config, overriding defaults
+                **worker.git_options,
+            },
         )
 
         f = builder_def.factory(