[0.9.1] Drop database deletes data/ directory

[PierreF]

On master (56d3add), when I issue a "DROP DATABASE name", the folder ~/.influxdb/data is removed, meaning all data files are removed. So after a restart (because influxdb keep some file opened) I've lost all data from all databases.

Version 0.9.1 is also affected.

Step to reproduce:

• clean ~/.influxdb to start from fresh setup (rm -fr ~/.influxdb)
• Start influxdb
• With UI, issue CREATE DATABASE db1 and CREATE DATABASE db2
• With UI, write into both database (I'm writting cpu_load_short,host=server01,region=us-west value=0.64 1434055562000000000, from the doc)
• Check with SHOW MEASUREMENTS that writes succeed.
• Also check that two folder "db1" and "db2" exists under ~/.influxdb/data
• With UI Issue DROP DATABASE db1
• Folder ~/.influxdb/data no longer exists ! (so db2's file are deleted from disk)
• Restart influxdb, db2 still exists but is empty (SHOW MEASUREMENTS return nothing)

[desa]

@pauldix @otoolep any ideas?

[otoolep]

One for @dgnorton, @jwilder and @benbjohnson too.

[otoolep]

Fixed by #3335

[otoolep]

@mjdesa -- we don't usually close issues until a PR is merged.

[otoolep]

Merged to master.

Thanks for the reports @mjdesa and @PierreF