podman generate systemd would create ill systemd unit files if using = in the --pod flag

[floating-cat]

Is this a BUG REPORT or FEATURE REQUEST? (leave only one on its own line)

/kind bug

Description
The podman generate systemd would create ill systemd unit files if I use = in the --pod flag.

Steps to reproduce the issue:

1. Run below commands:

podman pod create --name systemd-pod
podman create --pod=systemd-pod alpine top
podman generate systemd --new --name systemd-pod

2. The podman generate systemd will generate a systems unit file with this content:

ExecStart=/usr/bin/podman run --conmon-pidfile %t/container-agitated_elgamal.pid --cidfile %t/container-agitated_elgamal.ctr-id --cgroups=no-conmon --pod-id-file %t/pod-systemd-pod.pod-id -d --pod=systemd-pod alpine top

It uses --pod-id-file and --pod at the same time when running the podman.

Describe the results you received:
When running these generated systems unit files, the podman will show Cannot specify both --pod and --pod-id-file error and exit because of this: https://github.com/containers/libpod/blob/2df3faab7b2801cc2e3c2291b618ae530223329d/cmd/podman/common/specgen.go#L259

Describe the results you expected:
We can run this generated systems unit files without any problem.

Additional information you deem important (e.g. issue happens only occasionally):

If I use the following commands, the podman generate systemd will generate the correct systemd unit files.

podman pod create --name systemd-pod
podman create --pod systemd-pod alpine top
podman generate systemd --new --name systemd-pod

Output of podman version:

Version:      2.0.0
API Version:  1
Go Version:   go1.14.4
Git Commit:   eec482cae3289ecaad45c602629657da7062ce9c
Built:        Sat Jun 20 20:30:13 2020
OS/Arch:      linux/amd64

[vrothberg]

Thanks for the report, @floating-cat!

[vrothberg]

Opened #6768 to fix it.