all-contributors plugin log inconsistent with actual modifications to rc/README

**Describe the bug**

`all-contributors` plugin did not update README with all the contributors found.

**To Reproduce**

Will update this if i can reproduce, so far just happened on CI in a new repo

**Expected behavior**

All found contributors added to README/.all-contributorsrc

**Screenshots**
Release 1:
```
[2021-03-25T22:19:11.159Z] ℹ info Found contributions: { hborawski: Set { 'doc', 'infra', 'test', 'code' },
[2021-03-25T22:19:11.159Z] CIUSER: Set { 'doc' } }
[2021-03-25T22:19:11.159Z] ℹ info Adding "hborawski"'s contributions...
[2021-03-25T22:19:11.159Z] ℹ info Adding "CIUSER"'s contributions...
[2021-03-25T22:19:11.418Z] ✔ success Updated contributors!
[2021-03-25T22:19:11.418Z] M .all-contributorsrc
[2021-03-25T22:19:11.418Z] M README.md
```
only CIUSER was added to rc/readme

Release 2:
```
[2021-04-02T18:45:16.406Z] ℹ info Found contributions: { hborawski: Set { 'infra', 'doc', 'code' },
[2021-04-02T18:45:16.406Z] USER2: Set { 'code' } }
[2021-04-02T18:45:16.406Z] ℹ info Adding "hborawski"'s contributions...
[2021-04-02T18:45:16.406Z] ℹ info Adding "USER2"'s contributions...
[2021-04-02T18:45:16.665Z] ✔ success Updated contributors!
[2021-04-02T18:45:16.665Z] M .all-contributorsrc
[2021-04-02T18:45:16.665Z] M README.md
```

only USER2 was added to rc/readme

**Environment information:**

```txt

```

**Additional context**