Update get-poetry.py script

get-poetry.py

@@ -231,6 +231,7 @@ class Installer:
                     # Homebrew Python and possible other installations
                     # We workaround this issue by temporarily changing
                     # the --user directory
+                    original_user = os.getenv("PYTHONUSERBASE")
                     os.environ["PYTHONUSERBASE"] = dir
                     self.call(
                         self.CURRENT_PYTHON,
@@ -242,6 +243,11 @@ class Installer:
                         "--ignore-installed",
                     )
 
+                    if original_user is not None:
+                        os.environ["PYTHONUSERBASE"] = original_user
+                    else:
+                        del os.environ["PYTHONUSERBASE"]
+
                     # Finding site-package directory
                     lib = os.path.join(dir, "lib")
                     lib_python = list(glob(os.path.join(lib, "python*")))[0]