Fix url publication derivation for github users (closes #106).

The url is derived from the dev-repo field. This field can hold opam
"version control bound urls", which for mgithub means it can be
prefixed by 'git+' which is now chopped.

src-care/topkg_care_pkg.ml

@@ -44,6 +44,10 @@ let chop_ext u = match String.cut ~rev:true ~sep:"." u with
 | None -> u
 | Some (u, _) -> u
 
+let chop_git_prefix u = match String.cut ~sep:"git+" u with
+| Some ("", uri) -> uri
+| _ -> u
+
 (* Package *)
 
 type t =
@@ -199,7 +203,7 @@ let distrib_uri ?(raw = false) p =
               opam_field_hd p "dev-repo">>= function
               | None -> not_found ()
               | Some dev_repo ->
-                  Ok (uri_append (chop_ext dev_repo)
+                  Ok (uri_append (chop_git_prefix (chop_ext dev_repo))
                       "releases/download/$(VERSION)/$(NAME)-$(VERSION_NUM).tbz")
   in
   if raw then uri else subst_uri p uri

src/topkg.mli

@@ -1348,7 +1348,7 @@ let clean os ~build_dir = OS.Cmd.run @@ Pkg.clean_cmd os ~build_dir
          hostname of PKG_HOMEPAGE is [github] the following is used:
 {[PKG_DEV_REPO/releases/download/$(VERSION)/$(NAME)-$(VERSION_NUM).tbz]}
          where PKG_DEV_REPO is the package's opam file [dev-repo] field
-         without the [.git] suffix.}} *)
+         without the [.git] suffix and a possible [git+] prefix.}} *)
 
   val watermarks : watermark list
   (** [watermarks] is the default list of watermarks. It has the following