underscores are not allowed in `pkgver`

[dm7p]

The makedeb PKGBUILD syntax docs link to the Arch docs, which state:

[The pkgver] can contain letters, numbers, periods and underscores, but not a hyphen (-). If the author of the software uses one, replace it with an underscore (_).

I encountered a version like 1.1.1-15-g4d699d9 which I updated to 1.1.1_15_g4d699d9. However this returns:

[!] pkgver contains invalid characters.