Avoid infloop in python

Fix bug#24905

* lisp/progmodes/python.el (python-info-docstring-p): Improve
infloop avoidance: replace (bobp) with generic test for
forward progress.
* test/lisp/progmodes/python-tests.el (python-bob-infloop-avoid): Add
test for bug#24905

1 files changed, 7 insertions, 0 deletions

diff --git a/test/lisp/progmodes/python-tests.el b/test/lisp/progmodes/python-tests.el
index 54ed92212b8..f6564dd58cc 100644
--- a/test/lisp/progmodes/python-tests.el
+++ b/test/lisp/progmodes/python-tests.el
@@ -2452,6 +2452,13 @@ if x:
                 (line-beginning-position) (line-end-position))
                "abcdef")))))
 
+(ert-deftest python-bob-infloop-avoid ()
+  "Test that strings at BOB don't confuse syntax analysis.  Bug#24905"
+  (python-tests-with-temp-buffer
+      " \"\n"
+    (goto-char (point-min))
+    (font-lock-fontify-buffer)))
+
 
 ;;; Shell integration