iwatch: ignore EEXIST errors, we're already watching it
In particular this can happen from cgroup.c when multiple services map
to the same cgroup.events (due to being in the same cgroup)
@@ -94,6 +94,7 @@ int iwatch_add(struct iwatch *iw, char *file, uint32_t mask)
wd = inotify_add_watch(iw->fd, path, IWATCH_MASK | mask);
if (wd < 0) {
+ if (errno != EEXIST)
_pe("Failed adding watcher for %s", path);
free(path);
return -1;
