Add :hg build requirement.

Closes #19074.

1 files changed, 1 insertions, 0 deletions

diff --git a/Library/Homebrew/dependency_collector.rb b/Library/Homebrew/dependency_collector.rb
index 22f690a8c..bf5c014f3 100644
--- a/Library/Homebrew/dependency_collector.rb
+++ b/Library/Homebrew/dependency_collector.rb
@@ -91,6 +91,7 @@ class DependencyCollector
     when :tex        then TeXDependency.new(tag)
     when :clt        then CLTDependency.new(tag)
     when :arch       then ArchRequirement.new(tag)
+    when :hg         then MercurialDependency.new(tag)
     else
       raise "Unsupported special dependency #{spec}"
     end