Merge pull request #11 from valich/master

Add 2.6.0 sources and remove old preview versions

Author: os97673

README.md

@@ -22,11 +22,15 @@ To add another ruby version's source to this gem's directory:
 
     $ rake add_source VERSION=2.1.3 PATCHLEVEL=242
 
-(for pre-releases PATCHLEVEL should not be provided)
 add_source can use pre-downloaded .tgz (use TGZ_FILE_NAME to pass it)
 also it can extract patch level from version.h of downloaded sources, so
 PATCHLEVEL variable is optional.
 
+_Adding pre-release versions_. For pre-releases PATCHLEVEL should not be provided,
+as it is not present in distribution. To find sources of pre-release versions,
+this gem will look in `Debase::RubyCoreSource::REVISION_MAP` hash. Please add
+respective entry into this hash on adding pre-release version sources. 
+
 ## Credits
 
 * @valich for 2.5.0-preview1 headers and src-based ruby support

lib/debase/ruby_core_source.rb

@@ -4,9 +4,10 @@
 module Debase
   module RubyCoreSource
     REVISION_MAP = {
-      57064 => 'ruby-2.4.0-rc1',
-      60153 => 'ruby-2.5.0-preview1',
-      61243 => 'ruby-2.5.0-rc1',
+        # Add pre-release version here since they do not have patchlevel to refer to.
+        # Revision can be found at `revision.h` of ruby sources.
+        # Format of this hash:
+        # <RUBY_REVISION> => '<sources directory name>', e.g. `61243 => 'ruby-2.5.0-rc1'`
     }
 
     def self.create_makefile_with_core(hdrs, name)