Implement :checksum_hash mrbgem option.

This allows to use a mgem with a specific checksum hash.
The following modification were necessary to implement this
function:
  - add run_checkout build command to use 'git checkout'
  - skip shallow copy in case checksum_hash is used
  - make 'master' the default branch if branch isn't defined

1 files changed, 13 insertions, 1 deletions

diff --git a/tasks/mruby_build_gem.rake b/tasks/mruby_build_gem.rake
index 42d0d6b89..766266680 100644
--- a/tasks/mruby_build_gem.rake
+++ b/tasks/mruby_build_gem.rake
@@ -59,6 +59,9 @@ module MRuby
         url = params[:git]
         gemdir = "#{gem_clone_dir}/#{url.match(/([-\w]+)(\.[-\w]+|)$/).to_a[1]}"
 
+        # by default the 'master' branch is used
+        branch = params[:branch] ? params[:branch] : 'master'
+
         if File.exist?(gemdir)
           if $pull_gems
             git.run_pull gemdir, url
@@ -67,10 +70,19 @@ module MRuby
           end
         else
           options = [params[:options]] || []
-          options << "--branch \"#{params[:branch]}\"" if params[:branch]
+          options << "--branch \"#{branch}\""
+          options << "--depth 1" unless params[:checksum_hash]
           FileUtils.mkdir_p "#{gem_clone_dir}"
           git.run_clone gemdir, url, options
         end
+
+        if params[:checksum_hash]
+          # Jump to the specified commit
+          git.run_checkout gemdir, params[:checksum_hash]
+        else
+          # Jump to the top of the branch
+          git.run_checkout gemdir, branch
+        end
       else
         fail "unknown gem option #{params}"
       end