flasher: fastboot: take depends from pmaports.cfg

Adjust to avbtool now being part of android-tools in alpine edge.
Instead of trying to install both (which fails on edge), take the
dependencies from a new pmaports.cfg variable
supported_fastboot_depends, which only contains android-tools in
pmaports.git master branch.

Related: https://postmarketos.org/pmaports.cfg

pmb/config/__init__.py

@@ -829,7 +829,7 @@ uuu specific: $UUU_SCRIPT
 """
 flashers = {
     "fastboot": {
-        "depends": ["android-tools", "avbtool"],
+        "depends": [],  # pmaports.cfg: supported_fastboot_depends
         "actions": {
             "list_devices": [["fastboot", "devices", "-l"]],
             "flash_rootfs": [["fastboot", "flash", "$PARTITION_SYSTEM",

pmb/flasher/init.py

@@ -1,7 +1,8 @@
 # Copyright 2022 Oliver Smith
 # SPDX-License-Identifier: GPL-3.0-or-later
-import pmb.config
 import pmb.chroot.apk
+import pmb.config
+import pmb.config.pmaports
 import pmb.helpers.mount
 
 
@@ -19,8 +20,16 @@ def install_depends(args):
                            "Make sure, it is packaged for Alpine Linux, or"
                            " package it yourself, and then add it to"
                            " pmb/config/__init__.py.")
-    cfg = pmb.config.flashers[method]
-    pmb.chroot.apk.install(args, cfg["depends"])
+    depends = pmb.config.flashers[method]["depends"]
+
+    # Depends for some flash methods may be different for various pmaports
+    # branches, so read them from pmaports.cfg.
+    if method == "fastboot":
+        pmaports_cfg = pmb.config.pmaports.read_config(args)
+        depends = pmaports_cfg.get("supported_fastboot_depends",
+                                   "android-tools,avbtool").split(",")
+
+    pmb.chroot.apk.install(args, depends)
 
 
 def init(args):