bug#37071: guix import pypi httpie fails

[Robert Vollmert]

$ guix import pypi httpie
 …0.2.tar.gz  83KiB                   291KiB/s 00:00 [##################] 100.0%
 ….py3-none-any.whl  58KiB            201KiB/s 00:00 [##################] 100.0%
guix import: warning: Failed to extract file: httpie-1.0.2.dist-info/METADATA 
from wheel.
Backtrace:
          15 (primitive-load "/home/rob/.config/guix/current/bin/guix")
In guix/ui.scm:
  1692:12 14 (run-guix-command _ . _)
In guix/scripts/import.scm:
   115:11 13 (guix-import . _)
In guix/scripts/import/pypi.scm:
   102:23 12 (guix-import-pypi . _)
In guix/memoization.scm:
     98:0 11 (_ #<hash-table 11e5b20 0/31> ("httpie") _)
In unknown file:
          10 (_ #<procedure 11f9580 at guix/memoization.scm:179:32 …> …)
In ice-9/boot-9.scm:
    829:9  9 (catch _ _ #<procedure 7f2711b7fd48 at guix/import/pyp…> …)
In guix/utils.scm:
    635:8  8 (call-with-temporary-output-file _)
In guix/import/pypi.scm:
   384:25  7 (_ "/tmp/guix-file.A9OwRK" _)
In guix/utils.scm:
    635:8  6 (call-with-temporary-output-file #<procedure 1091c20 at…>)
In guix/import/utils.scm:
   133:10  5 (_ "/tmp/guix-file.jFzPxe" _)
    123:4  4 (url-fetch _ _)
In guix/build/download.scm:
    763:4  3 (url-fetch "/tmp/guix-file.A9OwRK" "/tmp/guix-file.jFz…" …)
In srfi/srfi-1.scm:
   679:15  2 (append-map _ _ . _)
   592:17  1 (map1 (#f))
In guix/build/download.scm:
    728:8  0 (maybe-expand-mirrors _ _)

guix/build/download.scm:728:8: In procedure maybe-expand-mirrors:
In procedure struct_vtable: Wrong type argument in position 1 (expecting 
struct): #f