git-svn migration fatal: not a valid SHA1 update-ref refs/heads/master refs/remotes/trunk: command returned error: 128
===

Trying to migrate a large but linear svn repository to git. The svn repository does not have the standard layout (trunk, branches, tags)...just one directory with the trunk.

Ubuntu 12.4 LTS,git 1.7.9.5.

    $ git svn clone https://coawstmodel.sourcerepo.com/coawstmodel/COAWST --authors-file=../users.txt COAWST
    
    ...
    
    	D	WPS/metgrid/storage_module.F
    	D	WPS/metgrid/process_domain_module.F
    W: -empty_dir: WPS/metgrid/gridinfo_module.F
    W: -empty_dir: WPS/metgrid/input_module.F
    W: -empty_dir: WPS/metgrid/interp_option_module.F
    W: -empty_dir: WPS/metgrid/module_date_pack.F
    W: -empty_dir: WPS/metgrid/process_domain_module.F
    W: -empty_dir: WPS/metgrid/storage_module.F
    r635 = c19181c9718e701788b540ed0cc559e4fbddf413 (refs/remotes/git-svn)
    	M	Tools/Docs/COAWST_User_Manual.doc
    r636 = 1b7849c3e5a20856c9ddb909a5f53ddf8501ad33 (refs/remotes/git-svn)
    Auto packing the repository for optimum performance. You may also
    run "git gc" manually. See "git help gc" for more information.
    Counting objects: 14143, done.
    Delta compression using up to 8 threads.
    Compressing objects: 100% (14039/14039), done.
    Writing objects: 100% (14143/14143), done.
    Total 14143 (delta 8350), reused 0 (delta 0)
    fatal: refs/remotes/trunk: not a valid SHA1
    update-ref refs/heads/master refs/remotes/trunk: command returned error: 128

I have tried variants with combinations of -s, -t Trunk, -t COAWST, --preserve-empty-dirs (which I would like to do), --no-meta-data (per Pro Git)...always the same final error.

Thanks for any suggestions!