COMP: Find Python3 once for wrapping builds

The component list no longer depends on a discovered version, so the
range search and the exact-version re-search collapse into one call.
NumPy now follows BUILD_TESTING consistently: the first search had
always demanded it, while only the second was checked.

Author: hjmjohnson

CMake/ITKSetPython3Vars.cmake

@@ -61,38 +61,6 @@ if(NOT PYTHON_DEVELOPMENT_REQUIRED)
   )
   set(ITK_WRAP_PYTHON_VERSION "ITK_WRAP_PYTHON=OFF")
 else()
-  # set(Python3_FIND_REGISTRY LAST) # default is FIRST. Do we need/want this?
-  find_package(
-    Python3
-    ${PYTHON_VERSION_MIN}...${PYTHON_VERSION_MAX}
-    COMPONENTS
-      Interpreter
-      # NOTE: dockcross build environments do not supply
-      #       `Development` python-dev resources
-      Development.SABIModule
-      NumPy
-  )
-  set(ITK_WRAP_PYTHON_VERSION "${Python3_VERSION}")
-
-  # An empty Python3_VERSION means the range found nothing; otherwise the second
-  # find_package below runs unversioned and silently accepts a below-floor Python.
-  if(
-    NOT
-      Python3_VERSION
-    OR
-      Python3_VERSION
-        VERSION_LESS
-        ${ITK_WRAP_PYTHON_MINIMUM_VERSION}
-  )
-    message(
-      FATAL_ERROR
-      "ITK Python wrapping (ITK_WRAP_PYTHON=ON) requires Python >= ${ITK_WRAP_PYTHON_MINIMUM_VERSION}, "
-      "but no such interpreter was found in range ${PYTHON_VERSION_MIN}...${PYTHON_VERSION_MAX} "
-      "(resolved version '${Python3_VERSION}', Python3_EXECUTABLE='${Python3_EXECUTABLE}'). "
-      "Provide a Python >= ${ITK_WRAP_PYTHON_MINIMUM_VERSION} interpreter, or set ITK_WRAP_PYTHON=OFF."
-    )
-  endif()
-
   # Wrapping requires this version and every module is abi3, so the wrapping
   # floor and the Limited API floor are the same number. Cached so
   # itk_end_wrap_module.cmake can pin USE_SABI to it.
@@ -123,13 +91,34 @@ else()
   endif()
   set(_missing_required_component FALSE)
   set(_missing_python_components "")
+  # set(Python3_FIND_REGISTRY LAST) # default is FIRST. Do we need/want this?
   find_package(
     Python3
-    ${ITK_WRAP_PYTHON_VERSION}
+    ${PYTHON_VERSION_MIN}...${PYTHON_VERSION_MAX}
     COMPONENTS
+      # NOTE: dockcross build environments do not supply
+      #       `Development` python-dev resources
       ${_python_find_components}
   )
   set(ITK_WRAP_PYTHON_VERSION "${Python3_VERSION}")
+
+  # An empty Python3_VERSION means the range found nothing.
+  if(
+    NOT
+      Python3_VERSION
+    OR
+      Python3_VERSION
+        VERSION_LESS
+        ${ITK_WRAP_PYTHON_MINIMUM_VERSION}
+  )
+    message(
+      FATAL_ERROR
+      "ITK Python wrapping (ITK_WRAP_PYTHON=ON) requires Python >= ${ITK_WRAP_PYTHON_MINIMUM_VERSION}, "
+      "but no such interpreter was found in range ${PYTHON_VERSION_MIN}...${PYTHON_VERSION_MAX} "
+      "(resolved version '${Python3_VERSION}', Python3_EXECUTABLE='${Python3_EXECUTABLE}'). "
+      "Provide a Python >= ${ITK_WRAP_PYTHON_MINIMUM_VERSION} interpreter, or set ITK_WRAP_PYTHON=OFF."
+    )
+  endif()
   message(STATUS "Python3_FOUND=${Python3_FOUND}")
   foreach(_required_component ${_python_find_components})
     if(NOT Python3_${_required_component}_FOUND)