Make storage_io_exception exception error message less cryptic by
actually including the human-readable error message from
std::system_error...
Before:
nodetool: Scylla API server HTTP POST to URL '/storage_service/snapshots' failed: Storage io error errno: 2
After:
nodetool: Scylla API server HTTP POST to URL '/storage_service/snapshots' failed: Storage I/O error: 2: No such file or directory
We can improve this further by including the name of the file that the I/O
error happened on.
Message-Id: <1465452061-15474-1-git-send-email-penberg@scylladb.com>