Don't error out when a package is already installed

Fixes Homebrew/homebrew#17010.

3 files changed, 6 insertions, 1 deletions

diff --git a/Library/Homebrew/cmd/install.rb b/Library/Homebrew/cmd/install.rb
index ef01d0452..f44f67091 100644
--- a/Library/Homebrew/cmd/install.rb
+++ b/Library/Homebrew/cmd/install.rb
@@ -91,6 +91,8 @@ module Homebrew extend self
   rescue FormulaInstallationAlreadyAttemptedError
     # We already attempted to install f as part of the dependency tree of
     # another formula. In that case, don't generate an error, just move on.
+  rescue FormulaAlreadyInstalledError => e
+    opoo e.message
   rescue CannotInstallFormulaError => e
     ofail e.message
   end
diff --git a/Library/Homebrew/exceptions.rb b/Library/Homebrew/exceptions.rb
index 43075003a..d57f5ddc3 100644
--- a/Library/Homebrew/exceptions.rb
+++ b/Library/Homebrew/exceptions.rb
@@ -71,6 +71,9 @@ end
 class CannotInstallFormulaError < RuntimeError
 end
 
+class FormulaAlreadyInstalledError < RuntimeError
+end
+
 class FormulaInstallationAlreadyAttemptedError < Homebrew::InstallationError
   def message
     "Formula installation already attempted: #{formula}"
diff --git a/Library/Homebrew/formula_installer.rb b/Library/Homebrew/formula_installer.rb
index 0b94c5b62..7f94b1d9e 100644
--- a/Library/Homebrew/formula_installer.rb
+++ b/Library/Homebrew/formula_installer.rb
@@ -34,7 +34,7 @@ class FormulaInstaller
     if f.installed?
       msg = "#{f}-#{f.installed_version} already installed"
       msg << ", it's just not linked" if not f.linked_keg.symlink? and not f.keg_only?
-      raise CannotInstallFormulaError, msg
+      raise FormulaAlreadyInstalledError, msg
     end
 
     # Building head-only without --HEAD is an error