Add CVSRequirement and SubversionRequirement

Use these two requirements in DependencyCollector.
Remove the unused function MacOS::Xcode.provides_cvs?

Library/Homebrew/dependency_collector.rb

@@ -159,7 +159,9 @@ class DependencyCollector
     elsif strategy <= BazaarDownloadStrategy
       Dependency.new("bazaar", tags)
     elsif strategy <= CVSDownloadStrategy
-      Dependency.new("cvs", tags) if MacOS.version >= :mavericks || !MacOS::Xcode.provides_cvs?
+      CVSRequirement.new(tags)
+    elsif strategy <= SubversionDownloadStrategy
+      SubversionRequirement.new(tags)
     elsif strategy < AbstractDownloadStrategy
       # allow unknown strategies to pass through
     else

Library/Homebrew/os/mac/xcode.rb

@@ -174,10 +174,6 @@ module OS
         version < "4.3"
       end
 
-      def provides_cvs?
-        version < "5.0"
-      end
-
       def default_prefix?
         if version < "4.3"
           prefix.to_s.start_with? "/Developer"

Library/Homebrew/requirements.rb

@@ -114,10 +114,15 @@ class ArchRequirement < Requirement
   end
 end
 
+class CVSRequirement < Requirement
+  fatal true
+  default_formula "cvs"
+  satisfy { which "cvs" }
+end
+
 class MercurialRequirement < Requirement
   fatal true
   default_formula "mercurial"
-
   satisfy { which("hg") }
 end
 
@@ -126,3 +131,9 @@ class GitRequirement < Requirement
   default_formula "git"
   satisfy { Utils.git_available? }
 end
+
+class SubversionRequirement < Requirement
+  fatal true
+  default_formula "subversion"
+  satisfy { Utils.svn_available? }
+end

Library/Homebrew/test/dependency_collector_spec.rb

@@ -84,6 +84,18 @@ describe DependencyCollector do
       expect(subject.add(resource)).to be_an_instance_of(GitRequirement)
     end
 
+    it "creates a resource dependency from a CVS URL" do
+      resource = Resource.new
+      resource.url(":pserver:anonymous:@example.com:/cvsroot/foo/bar", using: :cvs)
+      expect(subject.add(resource)).to be_an_instance_of(CVSRequirement)
+    end
+
+    it "creates a resource dependency from a Subversion URL" do
+      resource = Resource.new
+      resource.url("svn://example.com/foo/bar")
+      expect(subject.add(resource)).to be_an_instance_of(SubversionRequirement)
+    end
+
     it "creates a resource dependency from a '.7z' URL" do
       resource = Resource.new
       resource.url("http://example.com/foo.7z")