py3: Fix up (almost) all script invocations to rely on shebangs.

This follows up on 207cf6302 from last year to clean up cases that
have apparently popped up since then.  Invoking the scripts directly
makes a cleaner command line in any case, and moreover is essential
to how we control running a Zulip install as either Python 2 or 3
(soon, how we always ensure it runs as Python 3.)

One exception: we're currently forcing `provision` in dev to run
Python 3, while still running both Python 2 and Python 3 jobs in CI.
We use a non-shebang invocation to do the forcing of Python 3.

docs/migration-renumbering.md

@@ -85,9 +85,9 @@ semantic conflicts with the new changes from master:
 <output skipped>
 
   File "/srv/zulip-venv-cache/ad3a375e95a56d911510d7edba7e17280d227bc7/zulip-venv/local/lib/python2.7/site-packages/django/core/management/commands/migrate.py", line 105, in handle
-    "'python manage.py makemigrations --merge'" % name_str
+    "'./manage.py makemigrations --merge'" % name_str
 django.core.management.base.CommandError: Conflicting migrations detected (0026_topics_backfill, 0025_realm_message_content_edit_limit in zerver).
-To fix them run 'python manage.py makemigrations --merge'
+To fix them run './manage.py makemigrations --merge'
 
 <output skipped>
 

puppet/zulip/files/cron.d/update-analytics-counts

@@ -3,5 +3,5 @@ PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin
 USER=zulip
 
 # Run update analytics tables every 5 minutes past the hour
-5 * * * * zulip python /home/zulip/deployments/current/manage.py update_analytics_counts
+5 * * * * zulip /home/zulip/deployments/current/manage.py update_analytics_counts
 

tools/js-dep-visualizer.py

@@ -1,5 +1,6 @@
+#!/usr/bin/env python
 """
-$ python ./tools/js-dep-visualizer.py
+$ ./tools/js-dep-visualizer.py
 $ dot -Tpng var/zulip-deps.dot -o var/zulip-deps.png
 """
 

tools/provision

@@ -10,26 +10,28 @@ if [ "$EUID" -eq 0 ]; then
     exit 1
 fi
 
-if [ -n "$TRAVIS" ]; then
-    PYTHON=python
-else
-    PYTHON=python3
-fi
-
 #Make the script independent of the location from where it is
 #executed
 PARENT_PATH=$( cd "$(dirname "${BASH_SOURCE}")" ; pwd -P )
 cd "$PARENT_PATH"
 mkdir -p ../var/log
 LOG_PATH="../var/log/provision.log"
-PROVISION_PATH="lib/provision.py"
 
 echo "PROVISIONING STARTING." >> $LOG_PATH
 
+PROVISION_PATH="./lib/provision.py"
+if [ -n "$TRAVIS" ]; then
+    # In CI, we let PATH provide the Python version.
+    PROVISION_CMD=("$PROVISION_PATH")
+else
+    # In dev, we force Python 3.
+    PROVISION_CMD=(python3 "$PROVISION_PATH")
+fi
+
 # PYTHONUNBUFFERED is important to ensure that tracebacks don't get
 # lost far above where they should be in the output.
 export PYTHONUNBUFFERED=1
-"$PYTHON" "$PROVISION_PATH" "$@" 2>&1 | tee -a "$LOG_PATH"
+"${PROVISION_CMD[@]}" "$@" 2>&1 | tee -a "$LOG_PATH"
 failed=${PIPESTATUS[0]}
 
 if [ $failed = 1 ]; then

tools/test-all

@@ -41,9 +41,9 @@ run ./tools/run-mypy
 
 # travis/backend
 run ./tools/lint --pep8 $FORCEARG
-run python manage.py makemessages --locale en
+run ./manage.py makemessages --locale en
-run python -W ignore tools/check-capitalization --no-generate
+run PYTHONWARNINGS=ignore ./tools/check-capitalization --no-generate
-run python -W ignore tools/check-frontend-i18n --no-generate
+run PYTHONWARNINGS=ignore ./tools/check-frontend-i18n --no-generate
 run ./tools/test-tools
 run ./tools/test-backend $FORCEARG
 run ./tools/test-migrations

tools/travis/backend

@@ -6,9 +6,9 @@ set -e
 set -x
 
 ./tools/lint --pep8 # Include the slow and thus non-default pep8 linter check
-python manage.py makemessages --locale en
+./manage.py makemessages --locale en
-python -W ignore tools/check-capitalization --no-generate
+PYTHONWARNINGS=ignore ./tools/check-capitalization --no-generate
-python -W ignore tools/check-frontend-i18n --no-generate
+PYTHONWARNINGS=ignore ./tools/check-frontend-i18n --no-generate
 
 ./tools/test-tools
 ./tools/test-backend --coverage