releasetools: merge_target_files sets verbose in main.

The flag would otherwise be turned on unconditionally even when
importing merge_target_files as a module. As a result, `atest
releasetools_test` was broken / flaky prior to this change, as
PythonUnitTestResultParser doesn't like unexpected outputs in stderr.

Test: `atest releasetools_test releasetools_py3_test`
Change-Id: Ifd614c797d2cee3b33e4c2a7ad8e598850e9d60c
diff --git a/tools/releasetools/merge_target_files.py b/tools/releasetools/merge_target_files.py
index 81b95c8..cfffbc7 100755
--- a/tools/releasetools/merge_target_files.py
+++ b/tools/releasetools/merge_target_files.py
@@ -94,7 +94,6 @@
 logger = logging.getLogger(__name__)
 
 OPTIONS = common.OPTIONS
-OPTIONS.verbose = True
 OPTIONS.framework_target_files = None
 OPTIONS.framework_item_list = None
 OPTIONS.framework_misc_info_keys = None
@@ -1057,6 +1056,9 @@
     common.Usage(__doc__)
     sys.exit(1)
 
+  # Always turn on verbose logging.
+  OPTIONS.verbose = True
+
   if OPTIONS.framework_item_list:
     framework_item_list = common.LoadListFromFile(OPTIONS.framework_item_list)
   else: