cmd/root: Don't use podman(1) when generating the completions

Ever since commit bafbbe8, the shell completions are generated
while building Toolbx using the 'completion' command.  This involves
running toolbox(1) itself, and hence invoking 'podman version' to decide
if 'podman system migrate' is needed or not.

Unfortunately, some build environments, like Fedora's, are set up inside
a chroot(2) or systemd-nspawn(1) or similar, where 'podman version' may
not work because it does various things with namespaces(7) and clone(2)
that can, under certain circumstances, encounter an EPERM.

Therefore, it's better to avoid using podman(1) when generating the
shell completions, especially, since they are generated by Cobra itself
and podman(1) is not involved at all.

Note that podman(1) is needed when the generated shell completions are
actually used in interactive command line environments.  The shell
completions invoke the hidden '__complete' command to get the results
that are presented to the user, and, if needed, 'podman system migrate'
will continue to be run as part of that.

This partially reverts commit f3e005d
because podman(1) is now only an optional runtime dependency for the
system tests.

containers/podman#17657

meson.build

@@ -18,12 +18,12 @@ subid_dep = cc.find_library('subid', has_headers: ['shadow/subid.h'])
 
 go = find_program('go')
 go_md2man = find_program('go-md2man')
-podman = find_program('podman')
 
 bats = find_program('bats', required: false)
 codespell = find_program('codespell', required: false)
 htpasswd = find_program('htpasswd', required: false)
 openssl = find_program('openssl', required: false)
+podman = find_program('podman', required: false)
 shellcheck = find_program('shellcheck', required: false)
 skopeo = find_program('skopeo', required: false)
 

src/cmd/root.go

@@ -166,7 +166,7 @@ func preRun(cmd *cobra.Command, args []string) error {
 
 	logrus.Debugf("TOOLBOX_PATH is %s", toolboxPath)
 
-	if err := migrate(); err != nil {
+	if err := migrate(cmd, args); err != nil {
 		return err
 	}
 
@@ -211,13 +211,18 @@ func rootRun(cmd *cobra.Command, args []string) error {
 	return rootRunImpl(cmd, args)
 }
 
-func migrate() error {
+func migrate(cmd *cobra.Command, args []string) error {
 	logrus.Debug("Migrating to newer Podman")
 
 	if utils.IsInsideContainer() {
 		return nil
 	}
 
+	if cmdName, completionCmdName := cmd.Name(), completionCmd.Name(); cmdName == completionCmdName {
+		logrus.Debugf("Migration not needed: command %s doesn't need it", cmdName)
+		return nil
+	}
+
 	configDir, err := os.UserConfigDir()
 	if err != nil {
 		logrus.Debugf("Migrating to newer Podman: failed to get the user config directory: %s", err)