feat(system-update): Allow switching between branches via rebase

files/etc/ublue-update.d/system/00-system-update.py

@@ -3,6 +3,8 @@
 from subprocess import run
 from json import loads, load
 from json.decoder import JSONDecodeError
+from pathlib import Path
+
 import os
 
 
@@ -22,6 +24,18 @@ def check_for_rebase():
         print("uBlue image info file does not exist")
         return False, ""
 
+    # Branch away from the default tag when one is set
+    branch_file = Path("/var/ublue-update/branch")
+    if branch_file.exists():
+        with branch_file.open() as f:
+            branch = f.readline()
+            branch_file.unlink()
+            if branch:
+                return (
+                    True,
+                    f"{default_image_ref[0]}:{default_image_ref[1]}:{default_image_ref[2]}:{branch}",
+                )
+
     status_cmd = [
         "rpm-ostree",
         "status",

setup.cfg

@@ -23,4 +23,4 @@ install_requires =
 
 [flake8]
 max-line-length = 90
-ignore = E501
+ignore = E501,W503,W504