bpo-34055: Revert deletion of line in IDLE's PyShell (#11346)

The attribute is still used in other modules.

Lib/idlelib/pyshell.py

@@ -882,7 +882,7 @@ class PyShell(OutputWindow):
         self.usetabs = True
         # indentwidth must be 8 when using tabs.  See note in EditorWindow:
         self.indentwidth = 8
-
+        self.context_use_ps1 = True
         self.sys_ps1 = sys.ps1 if hasattr(sys, 'ps1') else '>>> '
         self.prompt_last_line = self.sys_ps1.split('\n')[-1]
         self.prompt = self.sys_ps1  # Changes when debug active

Misc/NEWS.d/next/IDLE/2018-12-28-17-16-33.bpo-34055.TmmpzR.rst

@@ -0,0 +1 @@
+Fix erroneous 'smart' indents and newlines in IDLE Shell.