Typo In Description of the Bug. It should be read as : 

On rhel nfs client loop mount of the image present in nfs share is not getting mounted **WITHOUT** _netdev option.

Can you please add debug to kernel cmdline, reproduce the issue and post here output of journalctl -b?

Yes, or you can just add thet directly during boot in grub.

Looking at the latest upstream fstab-generator, setting dependencies happens in the following:

                if (streq(me->mnt_type, "swap"))
                        k = add_swap(what, me,
                                     makefs*MAKEFS | growfs*GROWFS | noauto*NOAUTO | nofail*NOFAIL);
                else {
                        bool automount;
                        const char *post;

                        automount = fstab_test_option(me->mnt_opts,
                                                      "comment=systemd.automount\0"
                                                      "x-systemd.automount\0");
                        if (initrd)
                                post = SPECIAL_INITRD_FS_TARGET;
                        else if (mount_is_network(me))
                                post = SPECIAL_REMOTE_FS_TARGET;
                        else
                                post = SPECIAL_LOCAL_FS_TARGET;

                        k = add_mount(arg_dest,
                                      what,
                                      canonical_where ?: where,
                                      canonical_where ? where: NULL,
                                      me->mnt_type,
                                      me->mnt_opts,
                                      me->mnt_passno,
                                      makefs*MAKEFS | growfs*GROWFS | noauto*NOAUTO | nofail*NOFAIL | automount*AUTOMOUNT,
                                      post,
                                      fstab_path);
                }

Note that the "mount_is_network(me)" operation determines if the mount is to be tied to either the local-fs.target or remote-fs.target. That function evaluates as:

static bool mount_is_network(struct mntent *me) {
        assert(me);

        return fstab_test_option(me->mnt_opts, "_netdev\0") ||
               fstype_is_network(me->mnt_type);
}

And:

bool fstype_is_network(const char *fstype) {
        const char *x;

        x = startswith(fstype, "fuse.");
        if (x) 
                fstype = x;

        return STR_IN_SET(fstype,
                          "afs",
                          "cifs",
                          "smbfs",
                          "sshfs",
                          "ncpfs",
                          "ncp",
                          "nfs",
                          "nfs4",
                          "gfs",
                          "gfs2",
                          "glusterfs",
                          "pvfs2", /* OrangeFS */
                          "ocfs2",
                          "lustre");
}       


In lieu of setting "_netdev", the mechanism needed here would be a feature enhancement. Any feature of this type would have to be upstream first, to add awareness of parent filesystems. In other words, in the instance that you are mounting:

    parent /parent
    child  /parent/child

The expectation would be that if the parent filesystem is a network-requiring filesystem, then the child would not have a Before=local-fs.target directive. It would instead get a Before=remote-fs.target. I am more than a bit concerned that this implicit behaviour is much less ideal over the explicit use of the "_netdev" option. It would then result in odd child mount behaviours in the event that an incorrect "_netdev" configuration option is used in a parent mount.

As a result of the above state of the implementation, and that the initial investigation that started this bug report has been closed, I am closing this bug as WONTFIX in the RHEL 7 stream. In the event that demand is found to continue pursuit of this type of change, please open a subsequent bug report for RHEL 8 and reference this previous instance. From there, the guidance would be to file a request with the upstream project and pursue a solution there.