wrap: Don't use --branch with shallow clones against HEAD

Fixes #10931

Author: amyspark

mesonbuild/wrap/wrap.py

@@ -582,8 +582,11 @@ def get_git(self) -> None:
                         verbose_git(['fetch', self.wrap.get('url'), revno], self.dirname, check=True)
                         verbose_git(checkout_cmd, self.dirname, check=True)
             else:
-                verbose_git(['-c', 'advice.detachedHead=false', 'clone', *depth_option, '--branch', revno, self.wrap.get('url'),
-                             self.directory], self.subdir_root, check=True)
+                args = ['-c', 'advice.detachedHead=false', 'clone', *depth_option]
+                if revno.lower() != 'head':
+                    args += ['--branch', revno]
+                args += [self.wrap.get('url'), self.directory]
+                verbose_git(args, self.subdir_root, check=True)
             if self.wrap.values.get('clone-recursive', '').lower() == 'true':
                 verbose_git(['submodule', 'update', '--init', '--checkout', '--recursive', *depth_option],
                             self.dirname, check=True)

unittests/subprojectscommandtests.py

@@ -103,15 +103,20 @@ def _git_create_remote_tag(self, name, tag):
         self._git_remote(['commit', '--no-gpg-sign', '--allow-empty', '-m', f'tag {tag} commit'], name)
         self._git_remote(['tag', '--no-sign', tag], name)
 
-    def _wrap_create_git(self, name, revision='master'):
+    def _wrap_create_git(self, name, revision='master', depth=None):
         path = self.root_dir / name
         with open(str((self.subprojects_dir / name).with_suffix('.wrap')), 'w', encoding='utf-8') as f:
+            if depth is None:
+                depth_line = ''
+            else:
+                depth_line = 'depth = {}'.format(depth)
             f.write(textwrap.dedent(
                 '''
                 [wrap-git]
                 url={}
                 revision={}
-                '''.format(os.path.abspath(str(path)), revision)))
+                {}
+                '''.format(os.path.abspath(str(path)), revision, depth_line)))
 
     def _wrap_create_file(self, name, tarball='dummy.tar.gz'):
         path = self.root_dir / tarball
@@ -138,6 +143,14 @@ def test_git_update(self):
         self.assertPathExists(str(self.subprojects_dir / subp_name))
         self._git_config(self.subprojects_dir / subp_name)
 
+        # Create a fake remote git repository and a wrap file targeting
+        # HEAD and depth = 1. Checks that "meson subprojects download" works.
+        self._git_create_remote_repo(subp_name)
+        self._wrap_create_git(subp_name, revision='head', depth='1')
+        self._subprojects_cmd(['download'])
+        self.assertPathExists(str(self.subprojects_dir / subp_name))
+        self._git_config(self.subprojects_dir / subp_name)
+
         # Create a new remote branch and update the wrap file. Checks that
         # "meson subprojects update --reset" checkout the new branch.
         self._git_create_remote_branch(subp_name, 'newbranch')