[LNT] Python 3 support: Do not encode report for stdout

[thopre]

Summary

Daily report and run comparison are both output to stdout and sent by
email as attachment. Under Python 3's strict separation between text and
binary data the former needs to be done as a string while the latter
needs to be an encoded text, i.e. as binary data. This commit implements
that separation.

[PrzemekWirkus]

LGTM

[thopre]

Committed as 1c1509a497a4c3eb99a82900fb2bf2f64ffc71a9

lnt/lnttool/main.py

with contextlib.closing(config.get_database(database)) as db:
             filter_machine_regex=filter_machine_regex)
         report.build(session)
 
         logger.info("generating HTML report...")
         ts_url = "%s/db_%s/v4/%s" \
             % (config.zorgURL, database, testsuite)
         subject = "Daily Report: %04d-%02d-%02d" % (
             report.year, report.month, report.day)
-        html_report = report.render(ts_url, only_html_body=False).encode('utf-8')
+        html_report = report.render(ts_url, only_html_body=False)
+        utf8_html_report = html_report.encode('utf-8')
 
         if subject_prefix is not None:
             subject = "%s %s" % (subject_prefix, subject)
 
         # Form the multipart email message.
         msg = email.mime.multipart.MIMEMultipart('alternative')
         msg['Subject'] = subject
         msg['From'] = from_address
         msg['To'] = address
-        msg.attach(email.mime.text.MIMEText(html_report, 'html', 'utf-8'))
+        msg.attach(email.mime.text.MIMEText(utf8_html_report, 'html', 'utf-8'))
 
         # Send the report.
         if not dry_run:
             s = smtplib.SMTP(host)
             s.sendmail(from_address, [address],
                        msg.as_string())
             s.quit()
         else:
with contextlib.closing(config.get_database(database)) as db:
 
         # Generate the report.
         data = lnt.server.reporting.runs.generate_run_data(
             session, run_b, baseurl=config.zorgURL, result=None,
             compare_to=run_a, baseline=None, aggregation_fn=min)
 
         env = lnt.server.ui.app.create_jinja_environment()
         text_template = env.get_template('reporting/run_report.txt')
-        text_report = text_template.render(data).encode('utf-8')
+        text_report = text_template.render(data)
+        utf8_text_report = text_report.encode('utf-8')
         html_template = env.get_template('reporting/run_report.html')
-        html_report = html_template.render(data).encode('utf-8')
+        html_report = html_template.render(data)
+        utf8_html_report = html_report.encode('utf-8')
 
         subject = data['subject']
         if subject_prefix is not None:
             subject = "%s %s" % (subject_prefix, subject)
 
         # Form the multipart email message.
         msg = email.mime.multipart.MIMEMultipart('alternative')
         msg['Subject'] = subject
         msg['From'] = from_address
         msg['To'] = to_address
-        msg.attach(email.mime.text.MIMEText(text_report, 'plain', 'utf-8'))
-        msg.attach(email.mime.text.MIMEText(html_report, 'html', 'utf-8'))
+        msg.attach(email.mime.text.MIMEText(utf8_text_report, 'plain', 'utf-8'))
+        msg.attach(email.mime.text.MIMEText(utf8_html_report, 'html', 'utf-8'))
 
         # Send the report.
         if not dry_run:
             mail_client = smtplib.SMTP(host)
             mail_client.sendmail(
                 from_address,
                 [to_address],
                 msg.as_string())