openmolcas: fix shebangs in python scripts

patchShebangs replaces the shebang with the bare python
interpreter, but not with our defined environment.

This patch fixes the shebang manually and restores function
of all python scripts in $out/bin

pkgs/applications/science/chemistry/openmolcas/default.nix

@@ -159,9 +159,10 @@ stdenv.mkDerivation rec {
   noAuditTmpdir = true;
 
   postFixup = ''
-    # Wrong store path in shebang (no Python pkgs), force re-patching
-    sed -i "1s:/.*:/usr/bin/env python:" $out/bin/pymolcas
-    patchShebangs $out/bin
+    # Wrong store path in shebang (bare Python, no Python pkgs), force manual re-patching
+    for exe in $(find $out/bin/ -type f -name "*.py"); do
+      sed -i "1s:.*:#!${python}/bin/python:" "$exe"
+    done
 
     wrapProgram $out/bin/pymolcas --set MOLCAS $out
   '';