Fix src for financier

We accidentally used to rely on the src for financier not having been
garbage-collected.

default.nix

@@ -3,14 +3,12 @@
 }, system ? builtins.currentSystem}:
 
 let
-  meta = import ./meta.nix;
   derivations = import ./node2nix.nix {
     inherit pkgs system;
   };
 in
 derivations // {
   package = derivations.package.overrideAttrs (oldAttrs: rec {
-    src = pkgs.fetchgit { inherit (meta) url rev sha256; };
     # Puppeteer (a dependency for testing) would try to download Chromium
     # during installation. Downloading Chromium would not work though because
     # Nix builds are sandboxed and cannot download arbitrary things. We

generate.sh

@@ -2,4 +2,8 @@ node2nix "-$FINCANCIER_NODE_VERSION" --development \
 	--input "$FINANCIER_SRC/package.json" \
 	--lock "$FINANCIER_SRC/package-lock.json" \
 	--supplement-input supplement.json \
-	--composition node2nix.nix
+	--composition node2nix.nix
+
+# Fix the src attribute for the financier package
+pattern='\(\s*\).*'$(echo $FINANCIER_SRC | sed 's/\//\\\//g')'.*'
+sed -i "s/$pattern/\1src = (import .\/helpers.nix).fetchFinancier { inherit fetchgit; };/" node-packages.nix

helpers.nix

@@ -0,0 +1,4 @@
+{
+	fetchFinancier = { fetchgit, meta ? import ./meta.nix }:
+		fetchgit { inherit (meta) url rev sha256; };
+}

shell.nix

@@ -1,7 +1,7 @@
 { pkgs ? import <nixpkgs> {} }:
 let
 	meta = import ./meta.nix;
-	src = pkgs.fetchgit { inherit (meta) url rev sha256; };
+	src = (import ./helpers.nix).fetchFinancier { inherit (pkgs) fetchgit; inherit meta; };
 in
 pkgs.mkShell {
 	shellHook = ''