fix: restore revision support for orioledb builds (introduced it #1880)

Keep revision support that was accidentally simplified during nixpkgs update.
Restores conditional logic to support building orioledb from specific git
revision hashes instead of only tags.

Author: yvan-sraka

nix/postgresql/generic.nix

@@ -89,11 +89,17 @@ let
       pname = pname + lib.optionalString jitSupport "-jit";
 
       src =
-        if (isOrioleDB) then
-          fetchurl {
-            url = "https://github.com/orioledb/postgres/archive/refs/tags/patches${version}.tar.gz";
-            inherit hash;
-          }
+        if isOrioleDB then
+          if revision != null then
+            fetchurl {
+              url = "https://github.com/orioledb/postgres/archive/${revision}.tar.gz";
+              inherit hash;
+            }
+          else
+            fetchurl {
+              url = "https://github.com/orioledb/postgres/archive/refs/tags/patches${version}.tar.gz";
+              inherit hash;
+            }
         else
           fetchurl {
             url = "mirror://postgresql/source/v${version}/${pname}-${version}.tar.bz2";