[tex-live] Pretest tlmgr doesn't create user tree and cannot install thereinto

[tex_live at mmmmarascio.xyz]

Hello.  tlmgr from a TeX Live pretest installation seems to not work in user mode.  It won't create the user tree, e.g.,

$ tlmgr init-usertree
tlmgr: unknown action: init-usertree; try --help if you need it.

# TEXMFHOME=$HOME/.texlive/texmf
$ cd ~/.texlive && mkdir texmf && tlmgr init-usertree
tlmgr: unknown action: init-usertree; try --help if you need it.

Nor will tlmgr install into the user tree that it fails to create:

$ tlmgr --usermode install librarian
cannot setup TLPDB in /home/mmmm/.texlive/texmf at /usr/local/bin/tlmgr line 5330.

>From `tlmgr conf`: tlmgr revision 36854 (2015-04-14 14:08:59 +0200).  I obtained the pretest source from <http://mirror.hmc.edu/tlpretest>.
My operating system is Arch GNU/Linux.

$ uname --all
Linux maceta 3.19.3-3-ARCH #1 SMP PREEMPT Wed Apr 8 14:10:00 CEST 2015 x86_64 GNU/Linux

I can't think of other information that may be useful for investigating this matter.  But I'll gladly follow direction to provide anything else that may be relevant.  Thank you for any help!