cleanup, check history is enabled for repository

Author: vladak

opengrok-indexer/src/main/java/org/opengrok/indexer/history/RepositoryWithHistoryTraversal.java

@@ -95,7 +95,7 @@ protected void doCreateCache(HistoryCache cache, String sinceRevision, File dire
 
         FileCollector fileCollector = null;
         Project project = Project.getProject(directory);
-        if (project != null && isHistoryBasedReindex()) {
+        if (project != null && isHistoryBasedReindex() && isHistoryEnabled()) {
             // The fileCollector has to go through merge changesets no matter what the configuration says
             // in order to detect the files that need to be indexed.
             fileCollector = new FileCollector(true);

opengrok-indexer/src/main/java/org/opengrok/indexer/index/IndexDatabase.java

@@ -442,7 +442,6 @@ private static List<Repository> getRepositoriesForProject(Project project) {
 
     /**
      * @return whether the repositories of given project are ready for history based reindex
-     * TODO: move part of this to doCreateCache() (project specific and global checks)
      */
     private boolean isReadyForHistoryBasedReindex() {
         RuntimeEnvironment env = RuntimeEnvironment.getInstance();
@@ -478,7 +477,7 @@ private boolean isReadyForHistoryBasedReindex() {
 
         /*
          * Check that the index is present for this project.
-         * In such case the traversal of all changesets would most likely be counterproductive,
+         * In case of the initial indexing, the traversal of all changesets would most likely be counterproductive,
          * assuming traversal of directory tree is cheaper than getting the files from SCM history
          * in such case.
          */