keg: installed dependencies of unknown formulae

Previously, trying to resolve the dependencies of a keg would raise an
exception if the formulae for any of the dependencies could not be found
(e.g. if it had been moved to another tap).

This commit updates the dependency finding logic to catch these
exceptions, and fall back to comparing names and taps of formulae, which
should give the correct behaviour.

Fixes #1586.

1 files changed, 14 insertions, 3 deletions

diff --git a/Library/Homebrew/keg.rb b/Library/Homebrew/keg.rb
index 1de4ce1f0..3d2d21d69 100644
--- a/Library/Homebrew/keg.rb
+++ b/Library/Homebrew/keg.rb
@@ -139,6 +139,10 @@ class Keg
     raise NotAKegError, "#{path} is not inside a keg"
   end
 
+  def self.all
+    Formula.racks.flat_map(&:subdirs).map { |d| new(d) }
+  end
+
   attr_reader :path, :name, :linked_keg_record, :opt_record
   protected :path
 
@@ -353,14 +357,21 @@ class Keg
   end
 
   def installed_dependents
-    Formula.installed.flat_map(&:installed_kegs).select do |keg|
+    my_tab = Tab.for_keg(self)
+    Keg.all.select do |keg|
       tab = Tab.for_keg(keg)
       next if tab.runtime_dependencies.nil? # no dependency information saved.
       tab.runtime_dependencies.any? do |dep|
         # Resolve formula rather than directly comparing names
         # in case of conflicts between formulae from different taps.
-        dep_formula = Formulary.factory(dep["full_name"])
-        dep_formula == to_formula && dep["version"] == version.to_s
+        begin
+          dep_formula = Formulary.factory(dep["full_name"])
+          next false unless dep_formula == to_formula
+        rescue FormulaUnavailableError
+          next false unless my_tab["full_name"] = dep["full_name"]
+        end
+
+        dep["version"] == version.to_s
       end
     end
   end