After a bit of poking about I discovered that it is the git-subtree
installation option that is causing the dependency on libxslt.
I ran 'make config' to deselect this option, leaving all other options
in place, and git now builds/installs as usual when you build from the port.
This is certainly a workaround, but I don't love losing the ability to
have git-subtree option at my disposal.
Has there been any word at all on the remediation of this offending library?