After full backup passed on hdfs root and incremental failed, full backup cannot be cleaned

>>
./bin/hbase backup create full hdfs://localhost:8020/ -t test1

2017-09-27 10:19:38,885 INFO [main] impl.BackupManifest: Manifest file stored to hdfs://localhost:8020/backup_1506487766386/.backup.manifest
2017-09-27 10:19:38,937 INFO [main] impl.TableBackupClient: Backup backup_1506487766386 completed.
Backup session backup_1506487766386 finished. Status: SUCCESS

>>

2017-09-27 10:20:48,211 INFO [main] mapreduce.JobSubmitter: Cleaning up the staging area /tmp/hadoop-yarn/staging/vkhandelwal/.staging/job_1506419443344_0045
2017-09-27 10:20:48,215 ERROR [main] impl.TableBackupClient: Unexpected exception in incremental-backup: incremental copy backup_1506487845361Can not convert from directory (check Hadoop, HBase and WALPlayer M/R job logs)
java.io.IOException: Can not convert from directory (check Hadoop, HBase and WALPlayer M/R job logs)
at org.apache.hadoop.hbase.backup.impl.IncrementalTableBackupClient.walToHFiles(IncrementalTableBackupClient.java:363)
at

 ./bin/hbase backup create full hdfs://localhost:8020/ -t test1 

2017-09-27 10:19:38,885 INFO [main] impl.BackupManifest: Manifest file stored to hdfs://localhost:8020/backup_1506487766386/.backup.manifest
2017-09-27 10:19:38,937 INFO [main] impl.TableBackupClient: Backup backup_1506487766386 completed.
Backup session backup_1506487766386 finished. Status: SUCCESS

 ./bin/hbase backup create incremental hdfs://localhost:8020/ -t test1 

2017-09-27 10:20:48,215 ERROR [main] impl.TableBackupClient: Unexpected exception in incremental-backup: incremental copy backup_1506487845361Can not convert from directory (check Hadoop, HBase and WALPlayer M/R job logs)
java.io.IOException: Can not convert from directory (check Hadoop, HBase and WALPlayer M/R job logs)
at org.apache.hadoop.hbase.backup.impl.IncrementalTableBackupClient.walToHFiles(IncrementalTableBackupClient.java:363)
at org.apache.hadoop.hbase.backup.impl.IncrementalTableBackupClient.convertWALsToHFiles(IncrementalTableBackupClient.java:322)
at org.apache.hadoop.hbase.backup.impl.IncrementalTableBackupClient.execute(IncrementalTableBackupClient.java:232)
at org.apache.hadoop.hbase.backup.impl.BackupAdminImpl.backupTables(BackupAdminImpl.java:601)
at org.apache.hadoop.hbase.backup.impl.BackupCommands$CreateCommand.execute(BackupCommands.java:336)
at org.apache.hadoop.hbase.backup.BackupDriver.parseAndRun(BackupDriver.java:137)
at org.apache.hadoop.hbase.backup.BackupDriver.doWork(BackupDriver.java:170)
at org.apache.hadoop.hbase.backup.BackupDriver.run(BackupDriver.java:203)
at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:70)
at org.apache.hadoop.hbase.backup.BackupDriver.main(BackupDriver.java:178)
Caused by: java.lang.IllegalArgumentException: Can not create a Path from an empty string
at org.apache.hadoop.fs.Path.checkPathArg(Path.java:126)
at org.apache.hadoop.fs.Path.<init>(Path.java:134)
at org.apache.hadoop.util.StringUtils.stringToPath(StringUtils.java:245)
at org.apache.hadoop.hbase.mapreduce.WALInputFormat.getInputPaths(WALInputFormat.java:301)
at org.apache.hadoop.hbase.mapreduce.WALInputFormat.getSplits(WALInputFormat.java:274)
at org.apache.hadoop.hbase.mapreduce.WALInputFormat.getSplits(WALInputFormat.java:264)
at org.apache.hadoop.mapreduce.JobSubmitter.writeNewSplits(JobSubmitter.java:301)
at org.apache.hadoop.mapreduce.JobSubmitter.writeSplits(JobSubmitter.java:318)
at org.apache.hadoop.mapreduce.JobSubmitter.submitJobInternal(JobSubmitter.java:196)
at org.apache.hadoop.mapreduce.Job$10.run(Job.java:1290)
at org.apache.hadoop.mapreduce.Job$10.run(Job.java:1287)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:422)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1657)
at org.apache.hadoop.mapreduce.Job.submit(Job.java:1287)
at org.apache.hadoop.mapreduce.Job.waitForCompletion(Job.java:1308)
at org.apache.hadoop.hbase.mapreduce.WALPlayer.run(WALPlayer.java:380)
at org.apache.hadoop.hbase.backup.impl.IncrementalTableBackupClient.walToHFiles(IncrementalTableBackupClient.java:354)
... 9 more
2017-09-27 10:20:48,216 ERROR [main] impl.TableBackupClient: BackupId=backup_1506487845361,startts=1506487846725,failedts=1506487848216,failedphase=PREPARE_INCREMENTAL,failedmessage=Can not convert from directory (check Hadoop, HBase and WALPlayer M/R job logs)
2017-09-27 10:20:49,919 ERROR [main] impl.TableBackupClient: Backup backup_1506487845361 failed.
Backup session backup_1506487845361 finished. Status: SUCCESS

 ~/Desktop/backup-open-source/hbase-2.0.0-alpha3$ ./bin/hbase backup delete backup_150648776638 

Please make sure that backup is enabled on the cluster. To enable backup, in hbase-site.xml, set:
hbase.backup.enable=true
hbase.master.logcleaner.plugins=YOUR_PLUGINS,org.apache.hadoop.hbase.backup.master.BackupLogCleaner
hbase.procedure.master.classes=YOUR_CLASSES,org.apache.hadoop.hbase.backup.master.LogRollMasterProcedureManager
hbase.procedure.regionserver.classes=YOUR_CLASSES,org.apache.hadoop.hbase.backup.regionserver.LogRollRegionServerProcedureManager
and restart the cluster
2017-09-27 10:22:37,043 INFO [main] metrics.MetricRegistries: Loaded MetricRegistries class org.apache.hadoop.hbase.metrics.impl.MetricRegistriesImpl
Deleted 0 backups. Total requested: 2

 ./bin/hbase backup history | grep backup_150648776638 

2017-09-27 10:22:18,600 INFO [main] metrics.MetricRegistries: Loaded MetricRegistries class org.apache.hadoop.hbase.metrics.impl.MetricRegistriesImpl
{ID=backup_1506487766386,Type=FULL,Tables=

,State=COMPLETE,Start time=Wed Sep 27 10:19:27 IST 2017,End time=Wed Sep 27 10:19:38 IST 2017,Progress=100%}

So We should have 2 fixes here

#1 backup on root should not be allowed at all either full or incremental
#2 delete should work for any incorrect backup, as backup structure might be abstracted from user.