dev-cmd/contributions: Fix single-user handling; be more verbose

- `brew contributions --user=issyl0` was taking forever because it went
  through all maintainers first, because the conditionals were in the
  wrong order.
- This was too quiet, far too quiet, for something that takes so long.
- Now verbose mode tells you what repos it's scanning for a user.

Library/Homebrew/dev-cmd/contributions.rb

@@ -58,7 +58,15 @@ module Homebrew
       args.repositories
     end
 
-    return ofail "CSVs not yet supported for the full list of maintainers at once." if args.csv? && args.user.nil?
+    if args.user
+      user = args.user
+      results[user] = scan_repositories(repos, user, args)
+      puts "#{user} contributed #{total(results[user])} times #{time_period(args)}."
+      puts generate_csv(T.must(user), results[user]) if args.csv?
+      return
+    end
+
+    return ofail "CSVs not yet supported for the full list of maintainers at once." if args.csv?
 
     maintainers = GitHub.members_by_team("Homebrew", "maintainers")
     maintainers.each do |username, _|
@@ -71,13 +79,6 @@ module Homebrew
       results[username] = scan_repositories(repos, username, args)
       puts "#{username} contributed #{total(results[username])} times #{time_period(args)}."
     end
-
-    return unless args.user
-
-    user = args.user
-    results[user] = scan_repositories(repos, user, args)
-    puts "#{user} contributed #{total(results[user])} times #{time_period(args)}."
-    puts generate_csv(T.must(user), results[user]) if args.csv?
   end
 
   sig { params(repo: String).returns(Pathname) }
@@ -139,6 +140,8 @@ module Homebrew
         tap.full_name
       end
 
+      puts "Determining contributions for #{person} on #{repo_full_name}..." if args.verbose?
+
       data[repo] = {
         commits:       GitHub.repo_commit_count_for_user(repo_full_name, person),
         coauthorships: git_log_trailers_cmd(T.must(repo_path), "Co-authored-by", person, args),