[LNT] Python 3 support: adapt regex for div by 0 msg

Summary:
Test server/ui/V4Pages.py checks that the /explode page leads to a
division by zero exception message. However the exception message has
changed between Python 2 and Python 3 so this commit adapts the regex to
catch both texts.

Reviewers: cmatthews, hubert.reinterpretcast, kristof.beyls, leandron, PrzemekWirkus

Reviewed By: cmatthews

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D68988

Author: Thomas Preud'homme

tests/server/ui/V4Pages.py

@@ -636,7 +636,7 @@ def main():
     check_json(client, '/db_default/v4/nts/graph?switch_min_mean=yes&plot.0=1.3.2&json=true')
     app.testing = False
     error_page = check_html(client, '/explode', expected_code=500)
-    assert "integer division or modulo by zero" in error_page.data
+    assert re.search("division (or modulo )?by zero", error_page.data)
 
     error_page = check_html(client, '/gone', expected_code=404)
     assert "test" in error_page.data