Cannot set utc in <parse> section

[skaji]

Describe the bug

Cannot set utc in <parse> section:

❯ cat test.conf
<source>
  @type tail
  path test.log
  pos_file pos
  tag test
  <parse>
    @type json
    utc true
  </parse>
</source>

❯ fluentd --dry-run -c test.conf
2019-08-13 15:38:44 +0900 [info]: parsing config file is succeeded path="test.conf"
2019-08-13 15:38:44 +0900 [info]: starting fluentd-1.6.3 as dry run mode ruby="2.6.3"
2019-08-13 15:38:44 +0900 [error]: config error file="test.conf" error_class=Fluent::ConfigError error="both of utc and localtime are specified, use only one of them"

To Reproduce

• Prepare test.conf in "Describe the bug"
• Execute fluentd.

Expected behavior

Use UTC, and be able to run fluentd

Your Environment

• Fluentd or td-agent version

  ❯ fluentd --version
  fluentd 1.6.3
  

• Operating system

  ❯ sw_vers
  ProductName:	Mac OS X
  ProductVersion:	10.14.6
  BuildVersion:	18G84
  

• Kernel version

  ❯ uname -a
  Darwin MBP-19-002 18.7.0 Darwin Kernel Version 18.7.0: Thu Jun 20 18:42:21 PDT 2019; root:xnu-4903.270.47~4/RELEASE_X86_64 x86_64 i386 MacBookPro15,1 Darwin
  

Your Configuration

<source>
  @type tail
  path test.log
  pos_file pos
  tag test
  <parse>
    @type json
    utc true
  </parse>
</source>

Your Error Log

2019-08-13 15:38:44 +0900 [error]: config error file="test.conf" error_class=Fluent::ConfigError error="both of utc and localtime are specified, use only one of them"

Additional context

It seems that this bug has been fixed in #1319
Does it becomes a problem again?

[repeatedly]

Looks so. The problem line is here

fluentd/lib/fluent/time.rb

Line 158 in 5a7d949

conf['localtime'] = !(Fluent::Config.bool_value(conf['utc']))

and in_tail creates parser_create with conf argument.
So removing utc after converting to localtime or remove conf argument in in_tail resolve this problem. But I'm not sure this change breaks existing environment or not...