virt-install: Tell user where to find anaconda logs

People keep not realizing they exist, so let's print
a message about it.

src/gf-anaconda-cleanup

@@ -18,6 +18,18 @@ coreos_gf_run "${src}"
 coreos_gf set-label /dev/sda2 boot
 coreos_gf_run_mount "${src}"
 
+fb=/boot/ignition.firstboot
+exists=$(coreos_gf exists "${fb}")
+if [ "${exists}" = false ]; then
+    cat << EOF
+---------
+  error: Couldn't find ${fb} - most likely Anaconda failed."
+  error: If 9pfs is available, you can find logs in: tmp/build/tmp/anaconda"
+---------
+EOF
+    exit 1
+fi
+
 # Remove some things written by anaconda; eventually
 # we want to reset /etc except we also need /etc/fstab right now e.g.
 for x in "/etc/sysconfig/anaconda" "/etc/resolv.conf" "/etc/systemd/system/default.target"; do

src/virt-install

@@ -92,7 +92,10 @@ def get_libvirt_smp_arg():
 
 def run(fn, argv, **kwargs):
     print("cmd: {}".format(subprocess.list2cmdline(argv)))
-    return fn(argv, **kwargs)
+    try:
+        return fn(argv, **kwargs)
+    except subprocess.CalledProcessError as e:
+        raise SystemExit(f"{e}")
 
 def run_sync_verbose(argv, **kwargs):
     run(subprocess.check_call, argv, **kwargs)