feat: pin mbsync to version 4 (version 5 has a bug that prevents me from fetching my emails)

packages/isync/default.nix

@@ -0,0 +1,74 @@
+{
+  lib,
+  stdenv,
+  fetchurl,
+  pkg-config,
+  perl,
+  openssl,
+  db,
+  cyrus_sasl,
+  zlib,
+  # Disabled by default as XOAUTH2 is an "OBSOLETE" SASL mechanism and this relies
+  # on a package that isn't really maintained anymore:
+  withCyrusSaslXoauth2 ? false,
+  cyrus-sasl-xoauth2,
+  makeWrapper,
+}:
+
+stdenv.mkDerivation rec {
+  pname = "isync";
+  version = "1.4.4";
+
+  src = fetchurl {
+    url = "mirror://sourceforge/isync/${pname}-${version}.tar.gz";
+    sha256 = "1zq0wwvmqsl9y71546dr0aygzn9gjjfiw19hlcq87s929y4p6ckw";
+  };
+
+  patches = [
+    # Fixes "Fatal: buffer too small" error
+    ./0001-Increase-imap_vprintf-buffer-size.patch
+    # Fix #202595: SSL error "Socket error: ... unexpected eof while reading"
+    # Source: https://sourceforge.net/p/isync/isync/ci/b6c36624f04cd388873785c0631df3f2f9ac4bf0/
+    ./work-around-unexpected-EOF-error-messages-at-end-of-SSL-connections.patch
+  ];
+
+  nativeBuildInputs = [
+    pkg-config
+    perl
+  ] ++ lib.optionals withCyrusSaslXoauth2 [ makeWrapper ];
+  buildInputs = [
+    openssl
+    db
+    cyrus_sasl
+    zlib
+  ];
+
+  postInstall = lib.optionalString withCyrusSaslXoauth2 ''
+    wrapProgram "$out/bin/mbsync" \
+        --prefix SASL_PATH : "${
+          lib.makeSearchPath "lib/sasl2" [
+            cyrus-sasl-xoauth2
+            cyrus_sasl.out
+          ]
+        }"
+  '';
+
+  meta = with lib; {
+    homepage = "http://isync.sourceforge.net/";
+    # https://sourceforge.net/projects/isync/
+    changelog = "https://sourceforge.net/p/isync/isync/ci/v${version}/tree/NEWS";
+    description = "Free IMAP and MailDir mailbox synchronizer";
+    longDescription = ''
+      mbsync (formerly isync) is a command line application which synchronizes
+      mailboxes. Currently Maildir and IMAP4 mailboxes are supported. New
+      messages, message deletions and flag changes can be propagated both ways.
+    '';
+    license = licenses.gpl2Plus;
+    platforms = platforms.unix;
+    maintainers = with maintainers; [
+      primeos
+      lheckemann
+    ];
+    mainProgram = "mbsync";
+  };
+}