Fix cmake dependency issues with python package targets.

Refs #20381

qt/CMakeLists.txt

@@ -4,16 +4,24 @@ find_package ( QScintillaQt4 REQUIRED )
 include ( QtTargetFunctions )
 
 # Function to create links to python packages in the source tree
+# If the EXECUTABLE option is provided then it additional build rules are
+# defined to ensure startup scripts are regenerated appropriately
 function ( add_python_package pkg_name )
   # Create a setup.py file
   set ( _setup_py ${CMAKE_CURRENT_SOURCE_DIR}/setup.py )
   set ( _egg_link_dir ${CMAKE_LIBRARY_OUTPUT_DIRECTORY}/${CMAKE_CFG_INTDIR} )
   set ( _egg_link ${_egg_link_dir}/${pkg_name}.egg-link )
-  set ( _startup_script ${_egg_link_dir}/${pkg_name} )
-  if ( WIN32 )
-    set ( _startup_script ${_startup_script}.exe )
+  if ( ARGV0 EQUAL "EXECUTABLE" )
+      if ( WIN32 )
+        set ( _startup_script ${_egg_link_dir}/${pkg_name}-script.pyw )
+        set ( _startup_exe ${_egg_link_dir}/${pkg_name}.exe )
+      else ()
+        set ( _startup_script )
+        set ( _startup_exe ${_egg_link_dir}/${pkg_name} )
+      endif ()
   endif ()
-  add_custom_command ( OUTPUT ${_egg_link} ${_startup_script}
+  set ( _outputs "${_egg_link} ${_startup_script} ${_startup_exe}" )
+  add_custom_command ( OUTPUT ${_outputs}
     COMMAND ${CMAKE_COMMAND} -E env PYTHONPATH=${_egg_link_dir}
       ${PYTHON_EXECUTABLE} ${_setup_py} develop
       --install-dir ${CMAKE_LIBRARY_OUTPUT_DIRECTORY}/${CMAKE_CFG_INTDIR}
@@ -22,7 +30,7 @@ function ( add_python_package pkg_name )
     DEPENDS ${_setup_py}
   )
   add_custom_target ( ${pkg_name} ALL
-    DEPENDS ${_egg_link_dir}/${pkg_name} ${_egg_link}
+    DEPENDS ${_outputs}
   )
 endfunction ()
 

qt/applications/workbench/CMakeLists.txt

 # Creates egg link to binary output directory
-add_python_package ( workbench )
+add_python_package ( workbench EXECUTABLE )
 add_dependencies ( workbench mantidqt )
 
 # ctest targets