gh-103997: Remove incorrect statements about -c dedenting

Doc/using/cmdline.rst

@@ -49,7 +49,7 @@ additional methods of invocation:
   appropriately named script from that directory.
 * When called with ``-c command``, it executes the Python statement(s) given as
   *command*.  Here *command* may contain multiple statements separated by
-  newlines. Leading whitespace is significant in Python statements!
+  newlines.
 * When called with ``-m module-name``, the given module is located on the
   Python module path and executed as a script.
 
@@ -75,6 +75,8 @@ source.
 
    .. versionchanged:: 3.14
       *command* is automatically dedented before execution.
+      The auto-dedentation behavior only supports spaces and tabs,
+      and does not normalize empty lines.
 
 .. option:: -m <module-name>
 

Doc/whatsnew/3.14.rst

@@ -1188,8 +1188,8 @@ Other language changes
   (Contributed by Tomasz Pytel in :gh:`132329`.)
 
 * The command-line option :option:`-c` now automatically dedents its code
-  argument before execution. The auto-dedentation behavior mirrors
-  :func:`textwrap.dedent`.
+  argument before execution. The auto-dedentation behavior only
+  supports spaces and tabs and does not normalize empty lines.
   (Contributed by Jon Crall and Steven Sun in :gh:`103998`.)
 
 * Improve error message when an object supporting the synchronous

Include/internal/pycore_unicodeobject.h

@@ -258,7 +258,7 @@ extern Py_ssize_t _PyUnicode_InsertThousandsGrouping(
     int forward);
 
 /* Dedent a string.
-   Behaviour is expected to be an exact match of `textwrap.dedent`.
+   Only supports spaces and tabs and doesn't normalize empty lines.
    Return a new reference on success, NULL with exception set on error.
    */
 extern PyObject* _PyUnicode_Dedent(PyObject *unicode);

Misc/NEWS.d/3.14.0b1.rst

@@ -1881,8 +1881,10 @@ Improve error message when :exc:`TypeError` occurs during
 .. nonce: BS3uVt
 .. section: Core and Builtins
 
-String arguments passed to "-c" are now automatically dedented as if by
-:func:`textwrap.dedent`. This allows "python -c" invocations to be indented
+String arguments passed to "-c" are now automatically dedented.
+Only space-based and tab-based indentations are supported;
+empty lines are also not normalized.
+This allows "python -c" invocations to be indented
 in shell scripts without causing indentation errors. (Patch by Jon Crall and
 Steven Sun)
 

Objects/unicodeobject.c

@@ -14389,7 +14389,7 @@ search_longest_common_leading_whitespace(
 }
 
 /* Dedent a string.
-   Behaviour is expected to be an exact match of `textwrap.dedent`.
+   Only supports spaces and tabs and doesn't normalize empty lines.
    Return a new reference on success, NULL with exception set on error.
    */
 PyObject *