Bug#907415: tlmgr: unhelpful "Cannot determine type of tlpdb from /home/.../texmf!"

[Jakub Wilk <jwilk@jwilk.net>]

Package: texlive-base
Version: 2018.20180824-1
Severity: minor

Trying to learn how to use tlmgr was a bit unpleasant experience.
I first tried this:

  $ tlmgr update
  (running on Debian, switching to user mode!)
  Cannot determine type of tlpdb from /home/jwilk/texmf!
  cannot setup TLPDB in /home/jwilk/texmf at /usr/bin/tlmgr line 6513.

The error messages gave me no clue what is wrong.
OK, I found in the man page that I'm supposed to run init-usertree 
beforehand:

  $ tlmgr init-usertree
  (running on Debian, switching to user mode!)
  Cannot determine type of tlpdb from /home/jwilk/texmf!

This looks like it failed too, but it did in fact succeed.

Please make the messages more helpful, for example:

  $ tlmgr update
  (running on Debian, switching to user mode!)
  /home/jwilk/texmf does not exist; run "tlmgr init-usertree" first.

  $ tlmgr init-usertree
  Successfully initialized TLPDB in /home/jwilk/texmf/.


-- System Information:
Architecture: i386

Versions of packages texlive-base depends on:
ii  debconf           1.5.69
ii  tex-common        6.09
ii  libpaper-utils    1.1.24+nmu5
ii  sensible-utils    0.0.12
ii  texlive-binaries  2018.20180824.48463-1
ii  ucf               3.0038
ii  xdg-utils         1.1.3-1

--
Jakub Wilk