How do I fix a messed-up Guix?

[Konrad Hinsen]

Hi everyone,

since ¨guix pull" failed (see a recent message), I tried various ideas 
for getting back to a useable guix installation:

 - Build from a git checkout. Unfortunately, I cannot do "guix 
environment guix" anymore (like "guix pull", it tries to download 
python-2.7.12 and fails due to a hash mismatch). Running "./bootstrap" 
in my standard environment fails with an obscure error message about 
"autopoint" missing.

 - "guix package --roll-back" in the hope of going back to a state in 
which I can do "guix environment guix".

I ended up rolling back until my profile no longer contained "guix" (I 
have no idea how I could ever produce such a profile), so now I am 
completely stuck. Any idea for getting out of this mess?

Thanks in advance,
  Konrad.