git init not called when backfilling a package if fpm.toml file exists

[urbanjost]

If a default fpm.toml file is going to be built and the fpm.toml file already exists, the new subcommand stops with an instead of continuing with an , preventing the last action (calling "git init") from being called. This means git(1) is not initialized if the directory does not already have it set up; therefore skipping the last intended step. That is, if you simulate this by

fpm new  A
cd A
rm -rfv .git app
# simulated a hand-built fpm package without a src/ directory or git(1) that you want to backfill
fpm new --backfill
ls .git   # it is not there, and the backfill has an error message and a "STOP 3".