[PATCH] submodule.c: Make get_superproject_working_tree() work when supermodule has unmerged changes of the submodule reference

[Sam McKelvie <sammck@gmail.com>]

    Previously, "fatal: BUG: returned path string doesn't match cwd?" is displayed and
    git-rev-parse aborted.

    The problem is due to the fact that when a merge of the submodule reference is in progress,
    "git --stage —full-name <submodule-relative-path>” returns three seperate entries for the
    submodule (one for each stage) rather than a single entry; e.g.,

    $ git ls-files --stage --full-name submodule-child-test
    160000 dbbd2766fa330fa741ea59bb38689fcc2d283ac5 1       submodule-child-test
    160000 f174d1dbfe863a59692c3bdae730a36f2a788c51 2       submodule-child-test
    160000 e6178f3a58b958543952e12824aa2106d560f21d 3       submodule-child-test

    The code in get_superproject_working_tree() expected exactly one entry to be returned;
    this patch makes it use the first entry if multiple entries are returned.

    Signed-off-by: Sam McKelvie <smckelvie@xevo.com>
---
 submodule.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/submodule.c b/submodule.c
index 33de6ee5f..5b9d5ad7e 100644
--- a/submodule.c
+++ b/submodule.c
@@ -1885,7 +1885,7 @@ const char *get_superproject_working_tree(void)
 		 * We're only interested in the name after the tab.
 		 */
 		super_sub = strchr(sb.buf, '\t') + 1;
-		super_sub_len = sb.buf + sb.len - super_sub - 1;
+		super_sub_len = strlen(super_sub);
 
 		if (super_sub_len > cwd_len ||
 		    strcmp(&cwd[cwd_len - super_sub_len], super_sub))
-- 
2.19.0.605.g01d371f74.dirty