diff --git a/Library/Homebrew/download_strategy.rb b/Library/Homebrew/download_strategy.rb
index 417aee51ac..21eadabd30 100644
--- a/Library/Homebrew/download_strategy.rb
+++ b/Library/Homebrew/download_strategy.rb
@@ -1,5 +1,6 @@
 require 'open-uri'
 require 'utils/json'
+require 'erb'
 
 class AbstractDownloadStrategy
   attr_reader :name, :resource
@@ -33,6 +34,14 @@ class AbstractDownloadStrategy
     safe_system(*expand_safe_system_args(args))
   end
 
+  def checkout_name(tag)
+    if name.empty? || name == '__UNKNOWN__'
+      "#{ERB::Util.url_encode(@url)}--#{tag}"
+    else
+      "#{name}--#{tag}"
+    end
+  end
+
   # All download strategies are expected to implement these methods
   def fetch; end
   def stage; end
@@ -298,13 +307,11 @@ class SubversionDownloadStrategy < AbstractDownloadStrategy
     super
     @@svn ||= 'svn'
 
-    if name.to_s.empty? || name == '__UNKNOWN__'
-      raise NotImplementedError, "strategy requires a name parameter"
+    if ARGV.build_head?
+      @co = Pathname.new("#{HOMEBREW_CACHE}/#{checkout_name("svn-HEAD")}")
     else
-      @co = Pathname.new("#{HOMEBREW_CACHE}/#{name}--svn")
+      @co = Pathname.new("#{HOMEBREW_CACHE}/#{checkout_name("svn")}")
     end
-
-    @co = Pathname.new(@co.to_s + '-HEAD') if ARGV.build_head?
   end
 
   def cached_location
@@ -410,12 +417,7 @@ class GitDownloadStrategy < AbstractDownloadStrategy
   def initialize name, resource
     super
     @@git ||= 'git'
-
-    if name.to_s.empty? || name == '__UNKNOWN__'
-      raise NotImplementedError, "strategy requires a name parameter"
-    else
-      @clone = Pathname.new("#{HOMEBREW_CACHE}/#{name}--git")
-    end
+    @clone = Pathname.new("#{HOMEBREW_CACHE}/#{checkout_name("git")}")
   end
 
   def cached_location
@@ -562,13 +564,7 @@ end
 class CVSDownloadStrategy < AbstractDownloadStrategy
   def initialize name, resource
     super
-
-    if name.to_s.empty? || name == '__UNKNOWN__'
-      raise NotImplementedError, "strategy requires a name parameter"
-    else
-      @unique_token = "#{name}--cvs"
-      @co = Pathname.new("#{HOMEBREW_CACHE}/#{@unique_token}")
-    end
+    @co = Pathname.new("#{HOMEBREW_CACHE}/#{checkout_name("cvs")}")
   end
 
   def cached_location; @co; end
@@ -585,7 +581,7 @@ class CVSDownloadStrategy < AbstractDownloadStrategy
     unless @co.exist?
       Dir.chdir HOMEBREW_CACHE do
         safe_system '/usr/bin/cvs', '-d', url, 'login'
-        safe_system '/usr/bin/cvs', '-d', url, 'checkout', '-d', @unique_token, mod
+        safe_system '/usr/bin/cvs', '-d', url, 'checkout', '-d', checkout_name("cvs"), mod
       end
     else
       puts "Updating #{@co}"
@@ -618,12 +614,7 @@ end
 class MercurialDownloadStrategy < AbstractDownloadStrategy
   def initialize name, resource
     super
-
-    if name.to_s.empty? || name == '__UNKNOWN__'
-      raise NotImplementedError, "strategy requires a name parameter"
-    else
-      @clone = Pathname.new("#{HOMEBREW_CACHE}/#{name}--hg")
-    end
+    @clone = Pathname.new("#{HOMEBREW_CACHE}/#{checkout_name("hg")}")
   end
 
   def cached_location; @clone; end
@@ -678,12 +669,7 @@ end
 class BazaarDownloadStrategy < AbstractDownloadStrategy
   def initialize name, resource
     super
-
-    if name.to_s.empty? || name == '__UNKNOWN__'
-      raise NotImplementedError, "strategy requires a name parameter"
-    else
-      @clone = Pathname.new("#{HOMEBREW_CACHE}/#{name}--bzr")
-    end
+    @clone = Pathname.new("#{HOMEBREW_CACHE}/#{checkout_name("bzr")}")
   end
 
   def cached_location; @clone; end
@@ -731,11 +717,7 @@ end
 class FossilDownloadStrategy < AbstractDownloadStrategy
   def initialize name, resource
     super
-    if name.to_s.empty? || name == '__UNKNOWN__'
-      raise NotImplementedError, "strategy requires a name parameter"
-    else
-      @clone = Pathname.new("#{HOMEBREW_CACHE}/#{name}--fossil")
-    end
+    @clone = Pathname.new("#{HOMEBREW_CACHE}/#{checkout_name("fossil")}")
   end
 
   def cached_location; @clone; end
diff --git a/Library/Homebrew/test/test_download_strategies.rb b/Library/Homebrew/test/test_download_strategies.rb
index 3a330e7976..cdcb92dc94 100644
--- a/Library/Homebrew/test/test_download_strategies.rb
+++ b/Library/Homebrew/test/test_download_strategies.rb
@@ -2,7 +2,7 @@ require 'testing_env'
 require 'download_strategy'
 require 'bottles' # XXX: hoist these regexps into constants in Pathname?
 
-class SoftwareSpecDouble
+class ResourceDouble
   attr_reader :url, :specs
 
   def initialize(url="http://foo.com/bar.tar.gz", specs={})
@@ -14,8 +14,8 @@ end
 class AbstractDownloadStrategyTests < Test::Unit::TestCase
   def setup
     @name = "foo"
-    @package = SoftwareSpecDouble.new
-    @strategy = AbstractDownloadStrategy.new(@name, @package)
+    @resource = ResourceDouble.new
+    @strategy = AbstractDownloadStrategy.new(@name, @resource)
     @args = %w{foo bar baz}
   end
 
@@ -37,6 +37,32 @@ class AbstractDownloadStrategyTests < Test::Unit::TestCase
   end
 end
 
+class DownloadStrategyCheckoutNameTests < Test::Unit::TestCase
+  def setup
+    @resource = ResourceDouble.new("http://foo.com/bar")
+    @strategy = AbstractDownloadStrategy
+  end
+
+  def escaped(tag)
+    "#{ERB::Util.url_encode(@resource.url)}--#{tag}"
+  end
+
+  def test_explicit_name
+    downloader = @strategy.new("baz", @resource)
+    assert_equal "baz--foo", downloader.checkout_name("foo")
+  end
+
+  def test_empty_name
+    downloader = @strategy.new("", @resource)
+    assert_equal escaped("foo"), downloader.checkout_name("foo")
+  end
+
+  def test_unknown_name
+    downloader = @strategy.new("__UNKNOWN__", @resource)
+    assert_equal escaped("foo"), downloader.checkout_name("foo")
+  end
+end
+
 class DownloadStrategyDetectorTests < Test::Unit::TestCase
   def setup
     @d = DownloadStrategyDetector.new