Revert "wallabag: Drop swiftmailer patch"

The patch is still needed in 2.5.3.
It was removed because it did not apply to previous tarball,
which was accidentally generated from wrong branch.
It applies again after 2692bb8570.

This reverts commit 91391118c7.

pkgs/servers/web-apps/wallabag/default.nix

@@ -32,6 +32,14 @@ stdenv.mkDerivation {
 
   patches = [
     ./wallabag-data.patch # exposes $WALLABAG_DATA
+
+    # Use sendmail from php.ini instead of FHS path.
+    (fetchpatch {
+      url = "https://github.com/symfony/swiftmailer-bundle/commit/31a4fed8f621f141ba70cb42ffb8f73184995f4c.patch";
+      stripLen = 1;
+      extraPrefix = "vendor/symfony/swiftmailer-bundle/";
+      sha256 = "rxHiGhKFd/ZWnIfTt6omFLLoNFlyxOYNCHIv/UtxCho=";
+    })
   ];
 
   dontBuild = true;