Explain why we are using unpack

Author: mattias-ohlsson

lib/net/ldap/dataset.rb

@@ -139,6 +139,7 @@ def read_ldif(io)
           elsif line =~ /^dn:([\:]?)[\s]*/i
             # $1 is a colon if the dn-value is base-64 encoded
             # $' is the dn-value
+            # Avoid the Base64 class because not all Ruby versions have it.
             dn = ($1 == ":") ? $'.unpack('m').shift : $'
             ds[dn] = Hash.new { |k,v| k[v] = [] }
             yield :dn, dn if block_given?