i'm using Intellij, so for scenarios like this I create a separate "changelist" with name "LOCAL-ONLY" and include passwords and any local config that only applies to me.

That way I can clearly see that these changes don't get commited. You can also put line changes on the same file on different changelists.

Changelists concept is native with P4, but not sure with git. Maybe that's why Intellij only have it coz they've implemented their own on top of git.