[Bug #954364] inspect.getframeinfo() sometimes produces incorrect traceback...

[Bug #954364] inspect.getframeinfo() sometimes produces incorrect traceback line #s; fix is to look at tb.tb_lineno, not tb.frame.f_lineno.  Patch from Robin Becker and me.

Lib/inspect.py

@@ -740,12 +740,14 @@ def getframeinfo(frame, context=1):
     The optional second argument specifies the number of lines of context
     to return, which are centered around the current line."""
     if istraceback(frame):
+        lineno = frame.tb_lineno
         frame = frame.tb_frame
+    else:
+        lineno = frame.f_lineno
     if not isframe(frame):
         raise TypeError('arg is not a frame or traceback object')
 
     filename = getsourcefile(frame) or getfile(frame)
-    lineno = frame.f_lineno
     if context > 0:
         start = lineno - 1 - context//2
         try:

Lib/test/test_inspect.py

@@ -158,8 +158,8 @@ istest(inspect.istraceback, 'git.ex[2]')
 istest(inspect.isframe, 'mod.fr')
 
 test(len(git.tr) == 3, 'trace() length')
-test(git.tr[0][1:] == (TESTFN, 46, 'argue',
-                       ['            self.tr = inspect.trace()\n'], 0),
+test(git.tr[0][1:] == (TESTFN, 43, 'argue',
+                       ['            spam(a, b, c)\n'], 0),
      'trace() row 2')
 test(git.tr[1][1:] == (TESTFN, 9, 'spam', ['    eggs(b + d, c + f)\n'], 0),
      'trace() row 2')