Commit bf013c0 added support
for incorporating a commit ID into the compiled version string
but did so in a way that did not follow the semantic versioning
standard.

This commit corrects that flaw by moving the commit ID into the
"metadata" part of the version string and properly handles the
case where the commit hash cannot be retrieved.

XRPL Foundation's basic introduction to the XRPL, a great series that would *hopefully* continue...

A typographical error would mishandle the case where a caller explicitly
tries to remove a child that is not actually part of the node. This case
is never invoked in practice, and so the bug would will never trigger.