bug#33938: emacs-w3m build fails because of invalid git url

[Maxim Cournoyer]

Using Guix version 5895696e4c28938d9201e4527d3a007dd8b47e32, emacs-w3m
currently fails with:

--8<---------------cut here---------------start------------->8---
./pre-inst-env guix build emacs-w3m
building /gnu/store/gp0zp9fjwsks6qydybrw03yb2rl0ar98-git-checkout.drv...
environment variable `PATH' set to 
`/gnu/store/q09sy224qnxrp982z4xfaxi19721mjx8-gzip-1.9/bin:/gnu/store/ipx79bfj2mrc8npj7s3qi3zri11jfhaw-tar-1.30/bin'
Initialized empty Git repository in 
/gnu/store/wvbjysdw22ffjxxn3p45gwx01pmmfdfx-git-checkout/.git/
fatal: could not read Username for 'https://github.com': No such device or 
address
Failed to do a shallow fetch; retrying a full fetch...
fatal: could not read Username for 'https://github.com': No such device or 
address
Backtrace:
           3 (primitive-load "/gnu/store/b29qhm9vjrd3kvyip2jb7s34jkp?")
In ice-9/eval.scm:
   293:34  2 (_ #<directory (guile-user) 5ce140>)
In ./guix/build/git.scm:
    50:10  1 (git-fetch "https://github.com/ecbrown/emacs-w3m"; "0dd?" ?)
In ./guix/build/utils.scm:
    616:6  0 (invoke _ . _)

./guix/build/utils.scm:616:6: In procedure invoke:
Throw to key `srfi-34' with args `(#<condition &invoke-error [program: 
"/gnu/store/26s82xpawy0z13lfhkd7iprr2ahcbl5f-git-minimal-2.20.1/bin/git" 
arguments: ("fetch" "origin") exit-status: 128 term-signal: #f stop-signal: #f] 
5fb640>)'.
builder for `/gnu/store/gp0zp9fjwsks6qydybrw03yb2rl0ar98-git-checkout.drv' 
failed with exit code 1
build of /gnu/store/gp0zp9fjwsks6qydybrw03yb2rl0ar98-git-checkout.drv
failed
--8<---------------cut here---------------end--------------->8---

Attempting to visit its (non-official) Git repo confirms that the link
is broken: https://github.com/ecbrown/emacs-w3m.