Fix reppoints unmap fill bug

[zytx121]

Thanks for your contribution and we appreciate it a lot. The following instructions would make your pull request more healthy and more easily get feedback. If you do not understand some items, don't worry, just make the pull request and seek help from maintainers.

Motivation

resolve #592

Modification

Please briefly describe what modification is made in this PR.

BC-breaking (Optional)

Does the modification introduce changes that break the back-compatibility of the downstream repos?
If so, please describe how it breaks the compatibility and how the downstream projects should modify their code to keep compatibility with this PR.

Use cases (Optional)

If this PR introduces a new feature, it is better to list some use cases here, and update the documentation.

Checklist

1. Pre-commit or other linting tools are used to fix the potential lint issues.
2. The modification is covered by complete unit tests. If not, please add more unit test to ensure the correctness.
3. The documentation has been modified accordingly, like docstring or example tutorials.

[RangiLyu]

Need to rebase to the latest dev branch.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 3 lines in your changes are missing coverage. Please review.

Project coverage is 29.44%. Comparing base (bc1ced4) to head (3569b64).
Report is 13 commits behind head on dev.

Files	Patch %	Lines
...tate/models/dense_heads/oriented_reppoints_head.py	0.00%	1 Missing ⚠️
...otate/models/dense_heads/rotated_reppoints_head.py	0.00%	1 Missing ⚠️
mmrotate/models/dense_heads/sam_reppoints_head.py	0.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##              dev     #605   +/-   ##
=======================================
  Coverage   29.44%   29.44%           
=======================================
  Files         121      121           
  Lines        8500     8500           
  Branches     1279     1279           
=======================================
  Hits         2503     2503           
  Misses       5896     5896           
  Partials      101      101           

Flag	Coverage Δ
unittests	29.42% <0.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.