If the (redirected) channel URL contains a version number, use it

corepkgs/unpack-channel.nix

@@ -1,11 +1,11 @@
 with import <nix/config.nix>;
 
-{ name, src }:
+{ name, channelName, src }:
 
 derivation {
   system = builtins.currentSystem;
   builder = shell;
   args = [ "-e" ./unpack-channel.sh ];
-  inherit name src bzip2 tar tr;
+  inherit name channelName src bzip2 tar tr;
   PATH = "${nixBinDir}:${coreutils}";
 }

corepkgs/unpack-channel.sh

@@ -1,4 +1,4 @@
 mkdir $out
 cd $out
 $bzip2 -d < $src | $tar xf -
-mv * $out/$name
+mv * $out/$channelName

scripts/nix-channel.in

@@ -108,7 +108,13 @@ sub update {
         die "cannot fetch `$fullURL'" if $? != 0;
         chomp $path;
 
-        $exprs .= "'f: f { name = \"$name\"; src = builtins.storePath \"$path\"; }' ";
+        # If the URL contains a version number, append it to the name
+        # attribute (so that "nix-env -q" on the channels profile
+        # shows something useful).
+        my $cname = $name;
+        $cname .= $1 if basename($url) =~ /(-\d.*)$/;
+
+        $exprs .= "'f: f { name = \"$cname\"; channelName = \"$name\"; src = builtins.storePath \"$path\"; }' ";
     }
 
     # Unpack the channel tarballs into the Nix store and install them