check if debase installed (already_installed doesn't work)

Author: viuginick1

ext/mkrf_conf.rb

@@ -3,7 +3,11 @@
 
 def already_installed(dep)
   !Gem::DependencyInstaller.new(:domain => :local).find_gems_with_sources(dep).empty? ||
-  !Gem::DependencyInstaller.new(:domain => :local,:prerelease => true).find_gems_with_sources(dep).empty?    
+      !Gem::DependencyInstaller.new(:domain => :local,:prerelease => true).find_gems_with_sources(dep).empty?
+end
+
+def debase_installed
+  Gem::Specification.find_by_name('debase')
 end
 
 unless jruby || rbx
@@ -14,15 +18,17 @@ def already_installed(dep)
 
   begin
     Gem::Command.build_args = ARGV
-    rescue NoMethodError
+  rescue NoMethodError
   end
 
   if RUBY_VERSION < "1.9"
     dep = Gem::Dependency.new("ruby-debug-base", '>=0.10.4')
   elsif RUBY_VERSION < '2.0'
     dep = Gem::Dependency.new("ruby-debug-base19x", '>=0.11.30.pre15')
-  else    
+  else
     dep = Gem::Dependency.new("debase", '> 0')
+
+    return unless debase_installed
   end
 
   begin