ocrmypdf: prefer patch + substituteAll

pkgs/tools/text/ocrmypdf/default.nix

@@ -10,6 +10,7 @@
 , stdenv
 , tesseract4
 , unpaper
+, substituteAll
 }:
 
 let
@@ -68,11 +69,12 @@ in buildPythonApplication rec {
     setuptools
   ] ++ runtimeDeps;
 
-  postPatch = ''
+  patches = [
-    substituteInPlace src/ocrmypdf/leptonica.py \
+    (substituteAll {
-      --replace '_libpath = find_library(libname)' \
+      src = ./liblept.patch;
-                '_libpath = "${stdenv.lib.getLib leptonica}/lib/liblept${stdenv.hostPlatform.extensions.sharedLibrary}"'
+      liblept = "${stdenv.lib.getLib leptonica}/lib/liblept${stdenv.hostPlatform.extensions.sharedLibrary}";
-  '';
+    })
+  ];
 
   # The tests take potentially 20+ minutes, depending on machine
   doCheck = false;

pkgs/tools/text/ocrmypdf/liblept.patch

@@ -0,0 +1,13 @@
+diff --git a/src/ocrmypdf/leptonica.py b/src/ocrmypdf/leptonica.py
+index 328b063..b993cc9 100644
+--- a/src/ocrmypdf/leptonica.py
++++ b/src/ocrmypdf/leptonica.py
+@@ -46,7 +46,7 @@ if os.name == 'nt':
+     os.environ['PATH'] = shim_paths_with_program_files()
+ else:
+     libname = 'lept'
+-_libpath = find_library(libname)
++_libpath = '@liblept@'
+ if not _libpath:
+     raise MissingDependencyError(
+         """