log a warning if repository command does not work

Author: vladak

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

@@ -539,7 +539,10 @@ boolean isNestable() {
 
     private static boolean isHgWorking() {
         String repoCommand = getCommand(MercurialRepository.class, CMD_PROPERTY_KEY, CMD_FALLBACK);
-        return checkCmd(repoCommand);
+        boolean works = checkCmd(repoCommand);
+        LOGGER.log(Level.WARNING, "Command ''{0}'' does not work. " +
+                "Some operations with Mercurial repositories will fail as a result.", repoCommand);
+        return works;
     }
 
     @Override

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

@@ -364,7 +364,12 @@ boolean isRepositoryFor(File file, CommandTimeoutType cmdType) {
 
     private static boolean isSvnWorking() {
         String repoCommand = getCommand(SubversionRepository.class, CMD_PROPERTY_KEY, CMD_FALLBACK);
-        return checkCmd(repoCommand, "--help");
+        boolean works = checkCmd(repoCommand, "--help");
+        if (!works) {
+            LOGGER.log(Level.WARNING, "Command ''{0}'' does not work. " +
+                    "Some operations with Subversion repositories will fail as a result.", repoCommand);
+        }
+        return works;
     }
 
     @Override