when doing an devtool upgrade to an recipe getting it's source from git and contains an empty .gitmodules file the upgrade itself to the workspace works fine, but then devtool finish xxx xxx fails with this - probaly just a check if file is empty is enough...:

ERROR: ExpansionError during parsing /home/ubuntu/yocto/build/workspace/recipes/aws-c-common/aws-c-common_0.8.6.bb#####################################                                                                                                                                | ETA:  0:00:00
Traceback (most recent call last):
  File "Var <do_compile[file-checksums]>", line 1, in <module>
  File "/home/ubuntu/yocto/poky/meta/classes/externalsrc.bbclass", line 234, in srctree_hash_files(d=<bb.data_smart.DataSmart object at 0x7f034de03460>, srcdir=None):
                 if os.path.exists(os.path.join(s_dir, ".gitmodules")):
    >                submodule_helper = subprocess.check_output(["git", "config", "--file", ".gitmodules", "--get-regexp", "path"], cwd=s_dir, env=env).decode("utf-8")
                     for line in submodule_helper.splitlines():
  File "/usr/lib/python3.8/subprocess.py", line 415, in check_output(timeout=None, *popenargs=(['git', 'config', '--file', '.gitmodules', '--get-regexp', 'path'],), **kwargs={'cwd': '/home/ubuntu/yocto/build/workspace/sources/aws-c-common', 'env': {'SHELL': '/bin/bash', 'BB_ENV_PASSTHROUGH_ADDITIONS': 'ALL_PROXY BBPATH_EXTRA BB_LOGCONFIG BB_NO_NETWORK BB_NUMBER_THREADS BB_SETSCENE_ENFORCE BB_SRCREV_POLICY DISTRO FTPS_PROXY FTP_PROXY GIT_PROXY_COMMAND HTTPS_PROXY HTTP_PROXY MACHINE NO_PROXY PARALLEL_MAKE SCREENDIR SDKMACHINE SOCKS5_PASSWD SOCKS5_USER SSH_AGENT_PID SSH_AUTH_SOCK STAMPS_DIR TCLIBC TCMODE all_proxy ftp_proxy ftps_proxy http_proxy https_proxy no_proxy ', 'PWD': '/home/ubuntu/yocto/build', 'LOGNAME': 'ubuntu', 'HOME': '/home/ubuntu', 'BBPATH': '/home/ubuntu/yocto/build', 'USER': 'ubuntu', 'PATH': '/home/ubuntu/yocto/poky/scripts:/home/ubuntu/yocto/poky/bitbake/bin:/home/ubuntu/.local/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin', 'LC_ALL': 'en_US.UTF-8', 'GIT_INDEX_FILE': '/tmp/oe-devtool-indexn1tmjq6b'}}):
     
    >    return run(*popenargs, stdout=PIPE, timeout=timeout, check=True,
                    **kwargs).stdout
  File "/usr/lib/python3.8/subprocess.py", line 516, in run(input=None, capture_output=False, timeout=None, check=True, *popenargs=(['git', 'config', '--file', '.gitmodules', '--get-regexp', 'path'],), **kwargs={'stdout': -1, 'cwd': '/home/ubuntu/yocto/build/workspace/sources/aws-c-common', 'env': {'SHELL': '/bin/bash', 'BB_ENV_PASSTHROUGH_ADDITIONS': 'ALL_PROXY BBPATH_EXTRA BB_LOGCONFIG BB_NO_NETWORK BB_NUMBER_THREADS BB_SETSCENE_ENFORCE BB_SRCREV_POLICY DISTRO FTPS_PROXY FTP_PROXY GIT_PROXY_COMMAND HTTPS_PROXY HTTP_PROXY MACHINE NO_PROXY PARALLEL_MAKE SCREENDIR SDKMACHINE SOCKS5_PASSWD SOCKS5_USER SSH_AGENT_PID SSH_AUTH_SOCK STAMPS_DIR TCLIBC TCMODE all_proxy ftp_proxy ftps_proxy http_proxy https_proxy no_proxy ', 'PWD': '/home/ubuntu/yocto/build', 'LOGNAME': 'ubuntu', 'HOME': '/home/ubuntu', 'BBPATH': '/home/ubuntu/yocto/build', 'USER': 'ubuntu', 'PATH': '/home/ubuntu/yocto/poky/scripts:/home/ubuntu/yocto/poky/bitbake/bin:/home/ubuntu/.local/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin', 'LC_ALL': 'en_US.UTF-8', 'GIT_INDEX_FILE': '/tmp/oe-devtool-indexn1tmjq6b'}}):
             if check and retcode:
    >            raise CalledProcessError(retcode, process.args,
                                          output=stdout, stderr=stderr)
bb.data_smart.ExpansionError: Failure expanding variable do_compile[file-checksums], expression was ${@srctree_hash_files(d)} which triggered exception CalledProcessError: Command '['git', 'config', '--file', '.gitmodules', '--get-regexp', 'path']' returned non-zero exit status 1.
The variable dependency chain for the failure is: do_compile[file-checksums]