fix(npins): fetch dependencies from correct ref

We would previously get this error when fetching on new machines

… while fetching the input 'git+https://gerrit.wikimedia.org/r/mediawiki/extensions/AdvancedSearch?rev=398c9fa782843d8b3aeaa5ebb1c1b3db35c3382f'

error: Cannot find Git revision '398c9fa782843d8b3aeaa5ebb1c1b3db35c3382f' in ref 'refs/heads/master' of repository 'https://gerrit.wikimedia.org/r/mediawiki/extensions/AdvancedSearch'! Please make sure that the rev exists on the ref you've specified or add allRefs = true; to fetchGit.

Now, this is what I'd expect - because we're not meant to be fetching
master of this extension - we're meant to be fetching a branch! This
seems to be an issue with npins' fetchgit call, which misses out the ref

Due to a nilla bug, fetching dependencies is required for evaluation
so this prevented any evaluation

packetmix/npins/default.nix

···
                 url,
                 submodules,
                 rev,
+                branch ? null,
                 name,
                 narHash,
               }:
-              pkgs.fetchgit {
-                inherit url rev name;
-                fetchSubmodules = submodules;
-                hash = narHash;
-              };
+              pkgs.fetchgit (
+                {
+                  inherit url rev name;
+                  fetchSubmodules = submodules;
+                  hash = narHash;
+                }
+                // (
+                  if branch == null then
+                    { }
+                  else
+                    {
+                      ref = "refs/heads/${branch}";
+                    }
+                )
+              );
           };
 
       # Dispatch to the correct code path based on the type
···
       repository,
       revision,
       url ? null,
+      branch ? null,
       submodules,
       hash,
       ...
···
           "${if matched == null then "source" else builtins.head matched}${appendShort}";
         name = urlToName url revision;
       in
-      fetchGit {
-        rev = revision;
-        narHash = hash;
+      fetchGit (
+        {
+          rev = revision;
+          narHash = hash;
 
-        inherit name submodules url;
-      };
+          inherit name submodules url;
+        }
+        // (
+          if branch == null then
+            { }
+          else
+            {
+              ref = "refs/heads/${branch}";
+            }
+        )
+      );
 
   mkPyPiSource =
     { fetchurl, ... }:

packetmix/npins/sources.json

···
       "submodules": false,
       "revision": "12fb5f6d1a4bcfd1741b02fd60ec3c9ff6ec5faa",
       "url": null,
-      "hash": "sha256-vaSNVdiU9tLA5DujSFKAvY4fUiHVGEMvBzuswyPG22k="
+      "hash": "sha256-yks79QtWndY2+ESKFcO2EPlj886TDLV+DldK+GpiMXI="
     },
     "AutoCreateCategoryPages": {
       "type": "GitRelease",
···
       },
       "branch": "master",
       "submodules": false,
-      "revision": "f4e3698681704e74196fa0f905c7dfdd43cf5c86",
-      "url": "https://github.com/andir/npins/archive/f4e3698681704e74196fa0f905c7dfdd43cf5c86.tar.gz",
-      "hash": "sha256-8lkiistkBemkRN4aTqGW3SvI1CqibOnvFvNJS9OOdnU="
+      "revision": "0d6aaa4b3dcd1d8badbed2b66e0c50867330a86e",
+      "url": "https://github.com/andir/npins/archive/0d6aaa4b3dcd1d8badbed2b66e0c50867330a86e.tar.gz",
+      "hash": "sha256-9N14/tliOiA49Us2uFUWHcrhYN8AmJjR+bnwzcxejgs="
     },
     "scriptfs": {
       "type": "Git",