Inconsistent Behavior using 'Reference'

[Bret Barkelew <bret@corthon.com>]

The repo/workspace (not the cache, the code we’re going to build) that
we’re trying to initialize uses several submodules. We’ve notice that
if we use ‘clone’ first on the parent repository, then call ‘git
submodule update --init --recursive --reference <path>’ inside the
parent repository, the same path is passed to all child and nested
child repositories.

However, if we call ‘git clone --recurse-submodules --reference
<path>’ and try to clone the parent and initialize submodules in one
step, Git tries to append the submodule relative path (relative to the
parent) to each of the recursive calls, and since the reference repo
is bare, this fails.

CRITICAL - Cloning repo: https://github.com/Microsoft/mu_tiano_plus.git
INFO - Cmd to run is: git clone --recurse-submodules --reference
C:\src2\mu4\mu_basecore https://github.com/Microsoft/mu_tiano_plus.git
C:\src2\mu4\mu_basecore\Common\TIANO
INFO - ------------------------------------------------
INFO - --------------Cmd Output Starting---------------
INFO - ------------------------------------------------
INFO - Cloning into 'C:\src2\mu4\mu_basecore\Common\TIANO'...
Checking out files: 100% (3858/3858), done.
INFO - Submodule 'CryptoPkg/Library/OpensslLib/openssl'
(https://github.com/openssl/openssl) registered for path
'CryptoPkg/Library/OpensslLib/openssl'
INFO - fatal: submodule 'CryptoPkg/Library/OpensslLib/openssl' cannot
add alternate: path
'C:/src2/mu4/mu_basecore/.git/modules/CryptoPkg/Library/OpensslLib/openssl/'
does not exist
INFO - Failed to clone 'CryptoPkg/Library/OpensslLib/openssl'. Retry scheduled
INFO - fatal: submodule 'CryptoPkg/Library/OpensslLib/openssl' cannot
add alternate: path
'C:/src2/mu4/mu_basecore/.git/modules/CryptoPkg/Library/OpensslLib/openssl/'
does not exist
INFO - Failed to clone 'CryptoPkg/Library/OpensslLib/openssl' a second
time, aborting

As you can see, the parent path is
‘'C:\src2\mu4\mu_basecore\Common\TIANO’, but when clone initializes
the submodule, it updates the ‘C:\src2\mu4\mu_basecore’ reference to
‘C:/src2/mu4/mu_basecore/.git/modules/CryptoPkg/Library/OpensslLib/openssl/’,
as though the reference were a full repo and it was checking for the
submodule repo within the ‘.git’ directory.

If we do this same thing using a ‘clone’ first, and ‘submodule update’
second, the same ‘C:\src2\mu4\mu_basecore’ reference is passed to all
submodules (AND nested submodules).

Thoughts? Are these both expected behaviors? Will they be consistent
in future versions of git?

Thanks!

- Bret Barkelew