Manually merged branch "issue/601".

The commits in this branch would conflict with the current ones in the master
branch. I've modified the code of pry/completion.rb so that instead of escaping
*all* input it will only escape it when this hasn't already been done so.

This fixes #601.

Signed-off-by: Yorick Peterse <yorickpeterse@gmail.com>

lib/pry/completion.rb

@@ -74,8 +74,9 @@ class Pry
         when /^(:[^:.]*)$/
           # Symbol
           if Symbol.respond_to?(:all_symbols)
-            sym = $1
+            sym        = Regexp.quote($1)
             candidates = Symbol.all_symbols.collect{|s| ":" + s.id2name}
+
             candidates.grep(/^#{sym}/)
           else
             []

test/test_completion.rb

@@ -23,6 +23,13 @@ describe Pry::InputCompleter do
     end
   end
 
+  it 'should take parenthesis and other characters into account for symbols' do
+    b         = Pry.binding_for(Object.new)
+    completer = Pry::InputCompleter.build_completion_proc(b)
+
+    lambda { completer.call(":class)") }.should.not.raise(RegexpError)
+  end
+
   it 'should complete instance variables' do
     object = Object.new