implement change of pull request base command

                       
| Q             | A   |
| ---           | --- |
| Bug fix?      | n   |
| New feature?  | y   |
| BC breaks?    | n   |
| Deprecations? | n   |
| Tests pass?   | y   |
| Fixed tickets | #4  |
| License       | MIT |
| Doc PR        |     |
                       

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