Python console: do not require output that looks like a traceback to be valid

[birkenfeld]

which causes Error to be flagged with output that just happens to look like a traceback

Fixes #2407

[birkenfeld]

Note: alternate fix would be to just allow stray lines in PythonTracebackLexer.

[jeanas]

LGTM.

As you submitted this I was preparing a change that actually highlights these tracebacks “correctly” (e.g., Generic.Traceback for all "Traceback (...):" lines), but being robust is always good.

[Anteru]

The fix is fine, but it produces "one character tokens". Can we track if we're in "error mode" and while we're in error mode, accumulate tokens, and if we're in the first non-error token, yield the whole text accumulated so far? We can also fix this in a subsequent release if this is too much work for now and we want the fix out.

[jeanas]

Hmm, seems like the alternate fix would be better then?

If I understand correctly, it means

diff --git a/pygments/lexers/python.py b/pygments/lexers/python.py
index 6c89e6b5..eaaf6476 100644
--- a/pygments/lexers/python.py
+++ b/pygments/lexers/python.py
@@ -763,7 +763,8 @@ class PythonTracebackLexer(RegexLexer):
             (r'^([^:]+)(: )(.+)(\n)',
              bygroups(Generic.Error, Text, Name, Whitespace), '#pop'),
             (r'^([a-zA-Z_][\w.]*)(:?\n)',
-             bygroups(Generic.Error, Whitespace), '#pop')
+             bygroups(Generic.Error, Whitespace), '#pop'),
+            default('#pop'),
         ],
         'markers': [
             # Either `PEP 657 <https://www.python.org/dev/peps/pep-0657/>`

Right?

[birkenfeld]

Yeah, true, I like this better then.