RFR: 1828: RFR emails still be sent when PR is in draft state [v2]

[Guoxiong Li]

> Hi all,
> 
> This patch blocks the RFR email when new commits are pushed to a draft PR. And the test case is added. too.
> 
> But it doesn't solve the synchronization problem that Erik mentioned in [PR-1469](https://github.com/openjdk/skara/pull/1469#issuecomment-1425916242). Because the bot only generates one email one time regradless of the number of the commits.
> 
> Thanks for the review.
> 
> Best Regards,
> -- Guoxiong

Guoxiong Li has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains two additional commits since the last revision:

 - Merge branch 'master' into SKARA-1828
 - SKARA-1828

-------------

Changes:
  - all: https://git.openjdk.org/skara/pull/1484/files
  - new: https://git.openjdk.org/skara/pull/1484/files/d223a7d2..c8ae07c6

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=skara&pr=1484&range=01
 - incr: https://webrevs.openjdk.org/?repo=skara&pr=1484&range=00-01

  Stats: 5 lines in 1 file changed: 1 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/skara/pull/1484.diff
  Fetch: git fetch https://git.openjdk.org/skara pull/1484/head:pull/1484

PR: https://git.openjdk.org/skara/pull/1484