adjust backup-utils release script to better support patch branches

Author: JoeFranks1993

script/release

@@ -31,8 +31,8 @@ GH_REPO = ENV['GH_REPO'] || 'backup-utils'
 GH_OWNER = ENV['GH_OWNER'] || 'github'
 GH_AUTHOR = ENV['GH_AUTHOR']
 DEB_PKG_NAME = 'github-backup-utils'
-GH_BASE_BRANCH = ENV['GH_BASE_BRANCH'] || 'master'
-GH_STABLE_BRANCH = ENV['GH_STABLE_BRANCH'] || 'stable'
+GH_BASE_BRANCH = ENV['GH_BASE_BRANCH'] || 'master' # TODO: should we even allow a default or require all params get set explicitly?
+GH_STABLE_BRANCH = ""
 
 CHANGELOG_TMPL = '''<%= package_name %> (<%= package_version %>) UNRELEASED; urgency=medium
 
@@ -138,6 +138,7 @@ def beautify_changes(changes)
 end
 
 def changelog
+  puts "building changelog by comparing origin/#{GH_STABLE_BRANCH}...origin/#{GH_BASE_BRANCH}"
   changes = `git log --pretty=oneline origin/#{GH_STABLE_BRANCH}...origin/#{GH_BASE_BRANCH} --reverse --grep "Merge pull request" | sort -t\# -k2`.lines.map(&:strip)
   raise 'Building the changelog failed' if $CHILD_STATUS != 0
 
@@ -334,9 +335,31 @@ def clean_up(version)
   `git branch --quiet -D tmp-packaging >/dev/null 2>&1`
 end
 
+def is_base_branch_valid?(branch)
+  if branch == "master" || branch.match(/^\d+\.\d+-main$/)
+    return true
+  else
+    return false
+  end
+end
+
 #### All the action starts ####
 if $PROGRAM_NAME == __FILE__
   begin
+    ## validate base branch. this must either be "master" or a release branch which will match the pattern "x.y-main"
+    raise "The branch #{GH_BASE_BRANCH} is not valid for releasing backup-utils. branch name must be master or match x.y-main" if !is_base_branch_valid?(GH_BASE_BRANCH)
+
+    ## derive the proper stable branch. if the base branch is "master" the stable branch is just "stable"
+    ## if the base branch is a release branch, the stable branch will be "x.y-stable"
+    if GH_BASE_BRANCH == "master"
+      GH_STABLE_BRANCH = "stable"
+    else
+      GH_STABLE_BRANCH = GH_BASE_BRANCH.gsub(/-main$/, "-stable")
+    end
+
+    puts "base branch = " + GH_BASE_BRANCH
+    puts "stable branch = " + GH_STABLE_BRANCH
+
     args = ARGV.dup
     dry_run = false
     skip_version_bump_check = false
@@ -456,7 +479,7 @@ if $PROGRAM_NAME == __FILE__
     puts 'Cleaning up...'
     clean_up version
 
-    puts 'Updating stable branch...'
+    puts "Updating #{GH_STABLE_BRANCH} branch..."
     update_stable_branch
 
     puts 'Released!'