On Tue, 6 Feb 2018 14:54:06 -0800
Jonathan Tan [off-list ref] wrote:

quoted

There are two different possible solutions that have more value:
(a) The path value is documented as the path from the toplevel of the
    superproject to the mount point of the submodule.
    In this case we would want to have path='sub/nested'.

(b) As Ramsay noticed the documented value is wrong. For the non-nested
    case the path is equal to the relative path from $pwd to the
    submodules working directory. When following this model,
    the expected value would be path='../sub/nested'.

A third solution is to use "nested" - that is, the name of the submodule
directory relative to its superproject. (It's currently documented as
"the name of the submodule directory relative to the superproject".)
Having said that, (b) is probably better.

[snip]

quoted

+cat >expect <<EOF
+Entering '../nested1'
+$pwd/clone2-nested1-nested1-$nested1sha1
+Entering '../nested1/nested2'
+$pwd/clone2/nested1-nested2-nested2-$nested2sha1
+Entering '../nested1/nested2/nested3'
+$pwd/clone2/nested1/nested2-nested3-nested3-$nested3sha1
+Entering '../nested1/nested2/nested3/submodule'
+$pwd/clone2/nested1/nested2/nested3-submodule-submodule-$submodulesha1
+Entering '../sub1'
+$pwd/clone2-foo1-sub1-$sub1sha1
+Entering '../sub2'
+$pwd/clone2-foo2-sub2-$sub2sha1
+Entering '../sub3'
+$pwd/clone2-foo3-sub3-$sub3sha1
+EOF
+
+test_expect_success 'test "submodule foreach --recursive" from subdirectory' '
+	(
+		cd clone2/untracked &&
+		git submodule foreach --recursive "echo \$toplevel-\$name-\$sm_path-\$sha1" >../../actual
+	) &&
+	test_i18ncmp expect actual
+'

Wait a minute...this seems like you're using my "third solution". If we
were using either (a) or (b), $sm_path would contain slashes in the case
of nested submodules, right?