This example comes from Ian:

darcs get http://google.com/wibble
darcs failed:  Not a repository: http://google.com/wibble (Failed to download
URL http://google.com/wibble/_darcs/inventory: HTTP response code said error)

This could be better.  It could specifically says that we got a 404.

More generally, it should report the actual code we got

> More generally, it should report the actual code we got

...and the actual error text sent with the code, so that people won't 
have to Google for the meaning of (say) error code 402?

I've just submitted a patch for the issue. It employs a minor linguistic
hack, since I was trying to keep the original libcurl message intact,
but otherwise, should be OK:

$ /usr/bin/darcs --version
2.4.4 (release)
$ /usr/bin/darcs get http://google.com/wibble

darcs failed:  Not a repository: http://google.com/wibble (Failed to
download URL http://google.com/wibble/_darcs/inventory: HTTP response
code said error)
$ darcs --version
2.4.98.5 (+ 163 patches)
$ darcs get http://google.com/wibble

darcs failed:  Not a repository: http://google.com/wibble (HTTP response
code said error 404)

Note: I was expecting to find a _darcs/inventory file because I could
not find (or read) _darcs/format and assumed that the remote repository
is old-fashioned.

Actually, the 'Note' part of the new message is looking a bit weird, but
I didn't change it, I swear :) Not sure if it is worth filing another bug.

The following patch sent by Dmitry Tsygankov <dmitry.tsygankov@gmail.com> updated issue issue1637 with
status=resolved;resolvedin=2.8.0 HEAD

* resolve issue1637: report HTTP response code for HTTP errors 
Ignore-this: 67fcbd9a0d3466f21a3a045672a12218