Failure running "update gutter" on save (again)

[mnot]

After working for several years:

Update Gutter:35:in 'File#initialize': No such file or directory @ rb_sysopen - |${TM_GIT:-git} diff --no-color --no-ext-diff --"${TM_FILEPATH}" (Errno::ENOENT)
from Update Gutter:35:in 'Kernel#open'
from Update Gutter:35:in '<main>'