Use prefix comparison between paths, use UI.path for printing

lib/cocoapods/installer.rb

@@ -115,9 +115,9 @@ module Pod
 
     def prepare
       # Raise if pwd is inside Pods
-      if (Pathname.pwd <=> sandbox.root) >= 0
+      if Dir.pwd.start_with?(sandbox.root.to_path)
         message = 'Command should be run from a directory outside Pods directory.'
-        message << "\n\n\tCurrent directory is '#{Pathname.pwd}'\n"
+        message << "\n\n\tCurrent directory is #{UI.path(Pathname.pwd)}\n"
         raise Informative, message
       end
       UI.message 'Preparing' do

spec/unit/installer_spec.rb

@@ -166,11 +166,17 @@ module Pod
         UI.warnings.should.include 'BlocksKit has been deprecated'
       end
 
-      it 'raises if command is run inside sandbox directory' do
+      it 'does not raise if command is run outside sandbox directory' do
+        Dir.chdir(@installer.sandbox.root.parent) do
+          should.not.raise(Informative) { @installer.install! }
+        end
+      end
+
+      it 'raises if command is run in sandbox directory' do
         Dir.chdir(@installer.sandbox.root) do
           should.raise Informative do
             @installer.install!
-          end.message.should.match %r{should.*run.*outside.*Pods directory.*Current directory.*/Pods}m
+          end.message.should.match %r{should.*run.*outside.*Pods directory.*Current directory.*\.}m
         end
       end
     end