Merge pull request #13345 from Carreau/no-sys-path-append

Don't add ipython unconditionally to sys.path

IPython/core/application.py

@@ -185,6 +185,17 b' class BaseIPythonApplication(Application):'
                 get_ipython_package_dir(), u'config', u'profile', change['new']
         )
 
+    add_ipython_dir_to_sys_path = Bool(
+        False,
+        """Should the IPython profile directory be added to sys path ?
+
+        This option was non-existing before IPython 8.0, and ipython_dir was added to
+        sys path to allow import of extensions present there. This was historical
+        baggage from when pip did not exist. This now default to false,
+        but can be set to true for legacy reasons.
+        """,
+    ).tag(config=True)
+
     ipython_dir = Unicode(
         help="""
         The name of the IPython directory. This directory is used for logging
@@ -284,14 +295,17 b' class BaseIPythonApplication(Application):'
             str_old = os.path.abspath(old)
             if str_old in sys.path:
                 sys.path.remove(str_old)
+        if self.add_ipython_dir_to_sys_path:
         str_path = os.path.abspath(new)
         sys.path.append(str_path)
         ensure_dir_exists(new)
-        readme = os.path.join(new, 'README')
-        readme_src = os.path.join(get_ipython_package_dir(), u'config', u'profile', 'README')
+            readme = os.path.join(new, "README")
+            readme_src = os.path.join(
+                get_ipython_package_dir(), "config", "profile", "README"
+            )
         if not os.path.exists(readme) and os.path.exists(readme_src):
             shutil.copy(readme_src, readme)
-        for d in ('extensions', 'nbextensions'):
+            for d in ("extensions", "nbextensions"):
             path = os.path.join(new, d)
             try:
                 ensure_dir_exists(path)