cmd/update-report: do not fail when tap has no origin

This fixes the following error:

    $ brew update
    Warning: No remote 'origin' in /usr/local/Homebrew/Library/Taps/foo/homebrew-bar, skipping update!
    Error: HOMEBREW_UPDATE_BEFORE_FOO_HOMEBREW_BAR is unset!
    /usr/local/Homebrew/Library/Homebrew/cmd/update-report.rb:361:in `initialize'
    /usr/local/Homebrew/Library/Homebrew/cmd/update-report.rb:187:in `new'
    /usr/local/Homebrew/Library/Homebrew/cmd/update-report.rb:187:in `block in output_update_report'
    /usr/local/Homebrew/Library/Homebrew/tap.rb:748:in `block (2 levels) in each'
    /usr/local/Homebrew/Library/Homebrew/tap.rb:747:in `each'
    /usr/local/Homebrew/Library/Homebrew/tap.rb:747:in `block in each'
    /usr/local/Homebrew/Library/Homebrew/tap.rb:746:in `each'
    /usr/local/Homebrew/Library/Homebrew/tap.rb:746:in `each'
    /usr/local/Homebrew/Library/Homebrew/cmd/update-report.rb:160:in `output_update_report'
    /usr/local/Homebrew/Library/Homebrew/cmd/update-report.rb:40:in `update_report'
    /usr/local/Homebrew/Library/Homebrew/brew.rb:94:in `<main>'
    Already up-to-date.

Signed-off-by: Ruoyu Zhong <[email protected]>

Library/Homebrew/cmd/update-report.rb

@@ -158,7 +158,7 @@ def output_update_report
 
     updated_taps = []
     Tap.each do |tap|
-      next unless tap.git?
+      next if !tap.git? || tap.git_repo.origin_url.nil?
       next if (tap.core_tap? || tap == "homebrew/cask") && !Homebrew::EnvConfig.no_install_from_api?
 
       if ENV["HOMEBREW_MIGRATE_LINUXBREW_FORMULAE"].present? && tap.core_tap? &&