[LNT] Python 3 support: fix printing of exceptions

Summary:
A number of SQLAlchemy exception are printed by using their message
attribute. However PEP-352 deprecates this attribute from Python 2.6
onwards and drop it for Python 3 and later versions.

This commit replaces printing the message attribute by printing the
exception itself, relying on the __str__ method. This is actually
equivalent for exceptions with only a single argument (as required for
all exceptions on Python 3) as can be seen by the message property
getter in the aforementioned PEP.

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

Reviewed By: PrzemekWirkus

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D68798

Author: Thomas Preud'homme

lnt/server/db/migrations/upgrade_15_to_16.py

@@ -15,7 +15,7 @@ def _mk_index_on(engine, ts_name):
     try:
         fast_fc_lookup.create(engine)
     except (sqlalchemy.exc.OperationalError, sqlalchemy.exc.ProgrammingError) as e:
-        logger.warning("Skipping index creation on {}, because of {}".format(fc_table.name, e.message))
+        logger.warning("Skipping index creation on {}, because of {}".format(fc_table.name, e))
 
 
 def upgrade(engine):

lnt/server/db/migrations/upgrade_16_to_17.py

@@ -15,7 +15,7 @@ def _mk_index_on(engine, ts_name):
     try:
         fast_fc_lookup.create(engine)
     except (sqlalchemy.exc.OperationalError, sqlalchemy.exc.ProgrammingError) as e:
-        logger.warning("Skipping index creation on {}, because of {}".format(fc_table.name, e.message))
+        logger.warning("Skipping index creation on {}, because of {}".format(fc_table.name, e))
 
 
 def upgrade(engine):

lnt/tests/test_suite.py

@@ -637,7 +637,7 @@ def _lit(self, path, test, profile):
             return json.loads(open(output_json_path.name).read())
         except ValueError as e:
             fatal("Running test-suite did not create valid json report "
-                  "in {}: {}".format(output_json_path.name, e.message))
+                  "in {}: {}".format(output_json_path.name, e))
 
     def _is_pass_code(self, code):
         return code in ('PASS', 'XPASS', 'XFAIL')

lnt/util/ImportData.py

@@ -112,7 +112,7 @@ def import_and_report(config, db_name, db, session, file, format, ts_name,
         raise
     except Exception as e:
         import traceback
-        result['error'] = "import failure: %s" % e.message
+        result['error'] = "import failure: %s" % e
         result['message'] = traceback.format_exc()
         if isinstance(e, lnt.server.db.testsuitedb.MachineInfoChanged):
             result['message'] += \