I believe this would be compelled speech. Now, depending on the project and code change in question - the US govt could 1) fork and make the change themselves

I believe this would be compelled speech. Now, depending on the project and code change in question - the US govt could 1) fork and make the change themselves and 2) potentially make certain uses of the unchanged code illegal (again, in a situation where there is actual illegality. Like piracy).