python.el: Handle tabs in python-indent-dedent-line.

Fixes: debbugs:19730

* lisp/progmodes/python.el (python-indent-dedent-line): Fixes for
indentation with tabs.  Thanks to <dale@codefu.org>.

* test/automated/python-tests.el
(python-indent-dedent-line-backspace-2)
(python-indent-dedent-line-backspace-3): New tests.

lisp/ChangeLog

+2015-01-30  Fabián Ezequiel Gallina  <fgallina@gnu.org>
+
+	python.el: Handle tabs in python-indent-dedent-line.
+
+	* progmodes/python.el (python-indent-dedent-line): Fixes for
+	indentation with tabs.  Thanks to <dale@codefu.org> (Bug#19730).
+
 2015-01-30  Fabián Ezequiel Gallina  <fgallina@gnu.org>
 
 	* progmodes/python.el (python-indent-context): Respect user

lisp/progmodes/python.el

@@ -1067,9 +1067,7 @@ indentation levels from right to left."
   (interactive "*")
   (when (and (not (bolp))
            (not (python-syntax-comment-or-string-p))
-           (= (+ (line-beginning-position)
-                 (current-indentation))
-              (point)))
+           (= (current-indentation) (current-column)))
       (python-indent-line t)
       t))
 

test/ChangeLog

+2015-01-30  Fabián Ezequiel Gallina  <fgallina@gnu.org>
+
+	* automated/python-tests.el
+	(python-indent-dedent-line-backspace-2)
+	(python-indent-dedent-line-backspace-3): New tests.
+
 2015-01-30  Fabián Ezequiel Gallina  <fgallina@gnu.org>
 
 	* automated/python-tests.el (python-indent-pep8-1)

test/automated/python-tests.el

@@ -2127,6 +2127,55 @@ if True:
    (call-interactively #'python-indent-dedent-line-backspace)
    (should (zerop (current-indentation)))))
 
+(ert-deftest python-indent-dedent-line-backspace-2 ()
+  "Check de-indentation with tabs.  Bug#19730."
+  (let ((tab-width 8))
+    (python-tests-with-temp-buffer
+     "
+if x:
+\tabcdefg
+"
+     (python-tests-look-at "abcdefg")
+     (goto-char (line-end-position))
+     (call-interactively #'python-indent-dedent-line-backspace)
+     (should
+      (string= (buffer-substring-no-properties
+                (line-beginning-position) (line-end-position))
+               "\tabcdef")))))
+
+(ert-deftest python-indent-dedent-line-backspace-3 ()
+  "Paranoid check of de-indentation with tabs.  Bug#19730."
+  (let ((tab-width 8))
+    (python-tests-with-temp-buffer
+     "
+if x:
+\tif y:
+\t abcdefg
+"
+     (python-tests-look-at "abcdefg")
+     (goto-char (line-end-position))
+     (call-interactively #'python-indent-dedent-line-backspace)
+     (should
+      (string= (buffer-substring-no-properties
+                (line-beginning-position) (line-end-position))
+               "\t abcdef"))
+     (back-to-indentation)
+     (call-interactively #'python-indent-dedent-line-backspace)
+     (should
+      (string= (buffer-substring-no-properties
+                (line-beginning-position) (line-end-position))
+               "\tabcdef"))
+     (call-interactively #'python-indent-dedent-line-backspace)
+     (should
+      (string= (buffer-substring-no-properties
+                (line-beginning-position) (line-end-position))
+               "    abcdef"))
+     (call-interactively #'python-indent-dedent-line-backspace)
+     (should
+      (string= (buffer-substring-no-properties
+                (line-beginning-position) (line-end-position))
+               "abcdef")))))
+
 
 ;;; Shell integration