configure z3+python to build python libraries in its own prefix (#14604)

var/spack/repos/builtin/packages/z3/package.py

@@ -22,6 +22,7 @@ class Z3(MakefilePackage):
 
     variant('python', default=False, description='Enable python binding')
     depends_on('python', type=('build', 'run'))
+    extends('python', when='+python')
 
     # Referenced: https://github.com/Z3Prover/z3/issues/1016
     patch('fix_1016_1.patch', when='@:4.4.1')
@@ -31,9 +32,18 @@ class Z3(MakefilePackage):
 
     def configure_args(self):
         spec = self.spec
-        return [
-            '--python' if '+python' in spec else ''
-        ]
+
+        args = []
+
+        if spec.satisfies('+python'):
+            args.append('--python')
+            args.append(
+                '--pypkgdir=%s' % join_path(
+                    prefix.lib,
+                    'python%s' % spec['python'].version.up_to(2),
+                    'site-packages'))
+
+        return args
 
     def bootstrap(self, spec, prefix):
         options = ['--prefix={0}'.format(prefix)] + self.configure_args()