Correctly determine commit sha to avoid rebuilding PMD

In case the branch name was a tag, the tag sha was used instead of
the commit sha, which rebuilt PMD always.

Author: adangel

lib/pmdtester/builders/pmd_report_builder.rb

@@ -25,11 +25,14 @@ def initialize(projects, options, branch_config, branch_name)
     def get_pmd_binary_file
       logger.info "#{@pmd_branch_name}: Start packaging PMD"
       Dir.chdir(@local_git_repo) do
-        current_head_sha = Cmd.execute('git rev-parse HEAD')
-        current_branch_sha = Cmd.execute("git rev-parse #{@pmd_branch_name}")
+        current_head_sha = Cmd.execute('git rev-parse HEAD^{commit}')
+        current_branch_sha = Cmd.execute("git rev-parse #{@pmd_branch_name}^{commit}")
 
         @pmd_version = determine_pmd_version
 
+        logger.debug "pmd_version in HEAD: #{@pmd_version}, " \
+                     "head_sha=#{current_head_sha}, branch_sha=#{current_branch_sha}"
+
         # in case we are already on the correct branch
         # and a binary zip already exists...
         if current_head_sha == current_branch_sha &&

test/test_pmd_report_builder.rb

@@ -104,8 +104,8 @@ def record_expectations_project_build(error = false)
   def record_expectations(sha1_head, sha1_base, zip_file_exists)
     Dir.stubs(:getwd).returns('current-dir').once
     Dir.stubs(:chdir).with('target/repositories/pmd').yields.once
-    PmdTester::Cmd.stubs(:execute).with('git rev-parse HEAD').returns(sha1_head).once
-    PmdTester::Cmd.stubs(:execute).with('git rev-parse master').returns(sha1_base).once
+    PmdTester::Cmd.stubs(:execute).with('git rev-parse HEAD^{commit}').returns(sha1_head).once
+    PmdTester::Cmd.stubs(:execute).with('git rev-parse master^{commit}').returns(sha1_base).once
     PmdTester::Cmd.stubs(:execute).with('./mvnw -q -Dexec.executable="echo" ' \
                   "-Dexec.args='${project.version}' " \
                   '--non-recursive org.codehaus.mojo:exec-maven-plugin:1.5.0:exec')