Partial backport of r78826: leave import site error handler unchanged (print
the error and continue).

Merged revisions 78826-78827 via svnmerge from
svn+ssh://pythondev@svn.python.org/python/trunk

........
  r78826 | victor.stinner | 2010-03-10 23:30:19 +0100 (mer., 10 mars 2010) | 5 lines

  Issue #3137: Don't ignore errors at startup, especially a keyboard interrupt
  (SIGINT). If an error occurs while importing the site module, the error is
  printed and Python exits. Initialize the GIL before importing the site
  module.
........
  r78827 | victor.stinner | 2010-03-10 23:45:04 +0100 (mer., 10 mars 2010) | 4 lines

  ooops, fix error message in execusercustomize()

  Copy/paste failure :-)
........
diff --git a/Modules/main.c b/Modules/main.c
index 2d2bbf4..de0c851 100644
--- a/Modules/main.c
+++ b/Modules/main.c
@@ -569,10 +569,16 @@
 		}
 
 		if (sts==-1) {
-			sts = PyRun_AnyFileExFlags(
-				fp,
-				filename == NULL ? "<stdin>" : filename,
-				filename != NULL, &cf) != 0;
+			/* call pending calls like signal handlers (SIGINT) */
+			if (Py_MakePendingCalls() == -1) {
+				PyErr_Print();
+				sts = 1;
+			} else {
+				sts = PyRun_AnyFileExFlags(
+					fp,
+					filename == NULL ? "<stdin>" : filename,
+					filename != NULL, &cf) != 0;
+			}
 		}
 		
 	}