Fix test discovery crash in pytest adapter on doctest (lineno is None) (

microsoft#8920)

* FIX better handle unknown lineno in pytest discovery

* Add changelog entry

* Trigger CI to check potentially unrelated Heisen-failure

news/2 Fixes/7487.md

@@ -0,0 +1,2 @@
+Fix a crash when using pytest to discover doctests with unknown line number.
+(thanks [Olivier Grisel](https://github.com/ogrisel/))

pythonFiles/testing_tools/adapter/pytest/_pytest_item.py

@@ -274,14 +274,16 @@ def _get_location(item, testroot, relfile, #*,
                     # function to be in relfile.  So here we ignore any
                     # other file and just say "somewhere in relfile".
                     lineno = None
-            if lineno is None:
-                lineno = -1  # i.e. "unknown"
         elif _matches_relfile(srcfile, testroot, relfile):
             srcfile = relfile
         # Otherwise we just return the info from item.location as-is.
 
         if not srcfile.startswith('.' + _pathsep):
             srcfile = '.' + _pathsep + srcfile
+
+    if lineno is None:
+        lineno = -1  # i.e. "unknown"
+
     # from pytest, line numbers are 0-based
     location = '{}:{}'.format(srcfile, int(lineno) + 1)
     return location, fullname