Lower check of TOR_DISABLE_PRACTRACKER

Since we sometimes call practracker directly, that's where we should
check the TOR_DISABLE_PRACTRACKER envvar.

Makefile.am

@@ -369,9 +369,7 @@ endif
 
 check-best-practices:
 if USEPYTHON
-	@if test "$$TOR_DISABLE_PRACTRACKER" = ""; then \
+	@$(PYTHON) $(top_srcdir)/scripts/maint/practracker/practracker.py $(top_srcdir)
-		$(PYTHON) $(top_srcdir)/scripts/maint/practracker/practracker.py $(top_srcdir); \
-	fi
 endif
 
 practracker-regen:

scripts/maint/practracker/practracker.py

@@ -246,4 +246,6 @@ variable.
     sys.exit(found_new_issues)
 
 if __name__ == '__main__':
+    if os.environ.get("TOR_DISABLE_PRACTRACKER"):
+        sys.exit(0)
     main(sys.argv)