Improve region deletion handling in python.el

* lisp/progmodes/python.el (python-indent-dedent-line-backspace):
Delete the text in the region if Transient Mark mode is enabled,
the mark is active, and prefix arg is 1.  (Bug#48695)

* test/lisp/progmodes/python-tests.el
(python-indent-dedent-line-backspace-4): Add new test.

1 files changed, 6 insertions, 3 deletions

diff --git a/lisp/progmodes/python.el b/lisp/progmodes/python.el
index f4f0518dbfd..8b5ffae57d6 100644
--- a/lisp/progmodes/python.el
+++ b/lisp/progmodes/python.el
@@ -1967,10 +1967,13 @@ indentation levels from right to left."
 
 (defun python-indent-dedent-line-backspace (arg)
   "De-indent current line.
-Argument ARG is passed to `backward-delete-char-untabify' when
-point is not in between the indentation."
+Argument ARG is passed to `backward-delete-char-untabify' when point is
+not in between the indentation or when Transient Mark mode is enabled,
+the mark is active, and ARG is 1."
   (interactive "*p")
-  (unless (python-indent-dedent-line)
+  (when (or
+         (and (use-region-p) (= arg 1))
+         (not (python-indent-dedent-line)))
     (backward-delete-char-untabify arg)))
 
 (put 'python-indent-dedent-line-backspace 'delete-selection 'supersede)