Allow overriding pmaports path in pmbootstrap.cfg (!1728)

Make it possible to point the pmaports dir to an existing repository
clone, while not having to give the --aports/-p parameter with every
command.

  pmbootstrap --aports=/my/pmaports/path init

If the config file exists already, the dir can also be set with:

  pmbootstrap config aports /my/pmaports/path

pmb/config/__init__.py

@@ -47,11 +47,11 @@ pmaports_min_version = "1"
 # see migrate_work_folder()).
 work_version = 3
 
-# Only save keys to the config file, which we ask for in 'pmbootstrap init'.
+# Keys saved in the config file (mostly what we ask in 'pmbootstrap init')
 config_keys = ["ccache_size", "device", "extra_packages", "hostname", "jobs",
                "kernel", "keymap", "nonfree_firmware", "nonfree_userland",
                "qemu_native_mesa_driver", "ssh_keys", "timezone", "ui", "user",
-               "work"]
+               "work", "aports"]
 
 # Config file/commandline default values
 # $WORK gets replaced with the actual value for args.work (which may be

pmb/config/init.py

@@ -369,6 +369,9 @@ def frontend(args):
     # SSH keys
     cfg["pmbootstrap"]["ssh_keys"] = str(ask_for_ssh_keys(args))
 
+    # pmaports path (if users change it with: 'pmbootstrap --aports=... init')
+    cfg["pmbootstrap"]["aports"] = args.aports
+
     # Save config
     pmb.config.save(args, cfg)