chore(ci): share versionNameSuffix rewrite between merge paths

Extract `set_version_name_suffix()` and use it for both the `main->beta` and
`beta->release` merges. The release path now uses the same b\d+ pattern as
beta, so a beta past b9 no longer aborts the merge, and k9 starts at "b0"
like Thunderbird instead of "b1". This should be fine since we don't release
k9 beta, and the suffix gets dropped during a release for both apps.

Author: kryoseu

scripts/ci/merges/merge_gradle.py

@@ -8,6 +8,9 @@
 ours = sys.argv[1]
 theirs = sys.argv[2]
 
+BETA_SUFFIX = r"versionNameSuffix = \"b\d+\""
+MAIN_SUFFIX = r"versionNameSuffix = \"a1\""
+
 
 def get_current_branch():
     result = subprocess.run(
@@ -43,6 +46,24 @@ def replace_matching_line(file_path, search_term, new_line):
                 file.write(line)
 
 
+def set_version_name_suffix(file_path, search_term, suffix):
+    """Rewrites the versionNameSuffix line matching search_term.
+
+    Sets the suffix to `suffix`, or drops the line entirely when `suffix` is
+    None. Raises if the line is missing.
+    """
+    found_line = find_matching_line(file_path, search_term)
+    if not found_line:
+        raise SystemExit(f"Search term '{search_term}' not found in merge result.")
+    if suffix is None:
+        replace_matching_line(file_path, search_term, "")
+        return
+    if f'"{suffix}"' in found_line:
+        return
+    new_line = '{}= "{}"\n'.format(found_line.split("=")[0], suffix)
+    replace_matching_line(file_path, search_term, new_line)
+
+
 branch = get_current_branch()
 
 search_term = "com.fsck.k9"
@@ -62,28 +83,11 @@ def replace_matching_line(file_path, search_term, new_line):
     raise SystemExit(f"Search term '{search_term}' not found in ours file.")
 
 if branch == "beta":
-    if is_k9:
-        # main carries "a1";
-        search_term = r"versionNameSuffix = \"a1\""
-        found_line = find_matching_line(theirs, search_term)
-        if not found_line:
-            raise SystemExit(f"Search term '{search_term}' not found in theirs file.")
-        new_line = "{}{}\n".format(found_line.split("=")[0], '= "b1"')
-        replace_matching_line(ours, search_term, new_line)
-    else:
-        # beta always starts at "b0"; the shippable build workflow
-        # bumps the suffix per beta release.
-        search_term = r"versionNameSuffix = \"b\d+\""
-        found_line = find_matching_line(ours, search_term)
-        if not found_line:
-            raise SystemExit(f"Search term '{search_term}' not found in merge result.")
-        if '"b0"' not in found_line:
-            new_line = "{}{}\n".format(found_line.split("=")[0], '= "b0"')
-            replace_matching_line(ours, search_term, new_line)
+    # beta always starts at "b0"; the shippable build workflow bumps the suffix
+    # per beta release. k9 has no beta build, so main carries its suffix in
+    # defaultConfig as "a1" rather than "b0". The suffix is dropped on release
+    # for both apps below.
+    set_version_name_suffix(ours, MAIN_SUFFIX if is_k9 else BETA_SUFFIX, "b0")
 elif branch == "release":
-    search_term = r"versionNameSuffix = \"b[1-9]\""
-    found_line = find_matching_line(theirs, search_term)
-    if found_line:
-        replace_matching_line(ours, search_term, "")
-    else:
-        raise SystemExit(f"Search term '{search_term}' not found in theirs file.")
+    # release ships without a suffix, so drop the line beta was carrying.
+    set_version_name_suffix(ours, BETA_SUFFIX, suffix=None)