tab: set runtime_dependencies consistently.

Library/Homebrew/formula.rb

@@ -1523,8 +1523,9 @@ class Formula
        (keg = opt_or_installed_prefix_keg) &&
        (tab_deps = keg.runtime_dependencies)
       return tab_deps.map do |d|
-        next unless d["full_name"]
-        Dependency.new d["full_name"]
+        full_name = d["full_name"]
+        next unless full_name
+        Dependency.new full_name
       end.compact
     end
 

Library/Homebrew/formula_installer.rb

@@ -613,7 +613,7 @@ class FormulaInstaller
     # Update tab with actual runtime dependencies
     tab = Tab.for_keg(keg)
     Tab.clear_cache
-    tab.runtime_dependencies =
+    tab.runtime_dependency_objects =
       formula.runtime_dependencies(read_from_tab: false)
     tab.write
 

Library/Homebrew/tab.rb

@@ -33,10 +33,7 @@ class Tab < OpenStruct
       "compiler" => compiler,
       "stdlib" => stdlib,
       "aliases" => formula.aliases,
-      "runtime_dependencies" => runtime_deps.map do |dep|
-        f = dep.to_formula
-        { "full_name" => f.full_name, "version" => f.version.to_s }
-      end,
+      "runtime_dependencies" => Tab.runtime_deps_hash(runtime_deps),
       "source" => {
         "path" => formula.specified_path.to_s,
         "tap" => formula.tap&.name,
@@ -203,6 +200,13 @@ class Tab < OpenStruct
     new(attributes)
   end
 
+  def self.runtime_deps_hash(deps)
+    deps.map do |dep|
+      f = dep.to_formula
+      { "full_name" => f.full_name, "version" => f.version.to_s }
+    end
+  end
+
   def with?(val)
     option_names = val.respond_to?(:option_names) ? val.option_names : [val]
 
@@ -262,6 +266,10 @@ class Tab < OpenStruct
     super unless parsed_homebrew_version < "1.1.6"
   end
 
+  def runtime_dependency_objects=(deps)
+    source["runtime_dependencies"] = Tab.runtime_deps_hash(deps)
+  end
+
   def cxxstdlib
     # Older tabs won't have these values, so provide sensible defaults
     lib = stdlib.to_sym if stdlib