buildextend-live: unconditionally turn on osmet packing

This is the final step in ratcheting osmet into place for offline
installs by default. We drop the `--osmet` optional flag and now always
perform osmet packing when generating the live ISO.

(We could leave the switch around for a while just for compatibility,
but meh... the only other place this exists right now is the
coreos-installer CI, where we can trivially update it once this merges.)

Closes: coreos/fedora-coreos-tracker#352

.cci.jenkinsfile

@@ -52,6 +52,7 @@ pod(image: 'registry.fedoraproject.org/fedora:31', runAsUser: 0, kvm: true, memo
 
       stage("Image tests") {
         shwrap("cd /srv && env TMPDIR=\$(pwd)/tmp/ kola testiso -S")
+        shwrap("cd /srv && env TMPDIR=\$(pwd)/tmp/ kola testiso -S --scenarios iso-offline-install")
         // and again this time with the 4k image
         shwrap("cd /srv && env TMPDIR=\$(pwd)/tmp/ kola testiso -S --qemu-native-4k --no-pxe")
       }

src/cmd-buildextend-installer

@@ -43,9 +43,6 @@ parser = argparse.ArgumentParser()
 parser.add_argument("--build", help="Build ID")
 parser.add_argument("--force", action='store_true', default=False,
                     help="Overwrite previously generated installer")
-# Temporary switch while we ratchet osmet in place
-parser.add_argument("--osmet", action='store_true', default=False,
-                    help="Generate osmet file")
 args = parser.parse_args()
 
 # Identify the builds and target the latest build if none provided
@@ -174,13 +171,11 @@ def generate_iso():
         tmp_squashfs = os.path.join(tmpdir, 'root.squashfs')
         tmp_cpio = os.path.join(tmpdir, 'root.cpio')
         tmp_initramfs = os.path.join(tmpdir, 'initramfs')
-        cpio_input_files = [os.path.basename(tmp_squashfs)]
-        if args.osmet:
-            tmp_osmet = os.path.join(tmpdir, img_metal_obj['path'] + '.osmet')
-            cpio_input_files += [os.path.basename(tmp_osmet)]
-            print(f'Generating osmet file')
-            run_verbose(['/usr/lib/coreos-assembler/osmet-pack',
-                         img_metal, tmp_osmet, img_metal_checksum])
+        tmp_osmet = os.path.join(tmpdir, img_metal_obj['path'] + '.osmet')
+        cpio_input_files = [os.path.basename(f) for f in [tmp_squashfs, tmp_osmet]]
+        print(f'Generating osmet file')
+        run_verbose(['/usr/lib/coreos-assembler/osmet-pack',
+                     img_metal, tmp_osmet, img_metal_checksum])
 
         print(f'Compressing squashfs with {squashfs_compression}')
         run_verbose(['/usr/lib/coreos-assembler/gf-mksquashfs',