During migration, the tool simply copy/pasted the old submodule URL, which lead to inconsistencies such:
$ git clone --recursive git://git.code.sf.net/p/gdcm/gdcm Cloning into 'gdcm'... remote: Counting objects: 65664, done. remote: Compressing objects: 100% (13537/13537), done. remote: Total 65664 (delta 51934), reused 65658 (delta 51930) Receiving objects: 100% (65664/65664), 20.31 MiB | 2.32 MiB/s, done. Resolving deltas: 100% (51934/51934), done. Submodule 'Testing/Data' (git://gdcm.git.sourceforge.net/gitroot/gdcm/gdcmData) registered for path 'Testing/Data' Cloning into 'Testing/Data'... remote: Counting objects: 438, done. remote: Compressing objects: 100% (303/303), done. remote: Total 438 (delta 134), reused 428 (delta 131) Receiving objects: 100% (438/438), 160.33 MiB | 7.25 MiB/s, done. Resolving deltas: 100% (134/134), done. Submodule path 'Testing/Data': checked out 'ebd3260d5dd315dd99dae78c783c2fc1beb18f01'Well, this is not really an issue, we will just delete the old submodule and point to the new one.
Seems easy ? Well not quite, the new Allura does not cope with Upper case in name for mount point, so gdcmData needs to be gdcmdata now ...
Update: the following page explains how to delete (rm) submodule: