histdb-sync commits to git repo in parent dir

[diamond-lizard]

If a parent directory of $hist_dir contains a git repo, the first time histdb-sync runs, it'll try to commit to that repo, since the "git rev-parse --is-inside-work-tree" test will return true even if there's no git repo in $hist_dir itself.

Perhaps a simple test for the non-existence of a .git directory in $hist_dir would be more appropriate.

[LlinksRechts]

fixed this issue in pr #21