By the same way I know how the commit signers are who they say they are in "regular" usage of GPG: I have verified the key belongs to them, or their keys are si

By the same way I know how the commit signers are who they say they are in "regular" usage of GPG: I have verified the key belongs to them, or their keys are signed by people I trust to have verified, etc, etc. Like a sibling said, the problem is social rather than technical.