Don't close tsm cursor prematurely

We were closing the cursor when we read the last block which caused
the internal state to be cleared.  In a group by query, we seeked multiple
times so depending on the group by interval and how the data was laid out
in the blocks, we woudl close the cursor and the last block would get skipped.

Fixes influxdata#5193

CHANGELOG.md

@@ -25,6 +25,7 @@ With this release InfluxDB is moving to Go 1.5.
 - [#5158](https://github.com/influxdb/influxdb/pull/5158): Fix panic when writing invalid input to the line protocol.
 - [#5264](https://github.com/influxdata/influxdb/pull/5264): Fix panic: runtime error: slice bounds out of range
 - [#5186](https://github.com/influxdata/influxdb/pull/5186): Fix database creation with retention statement parsing. Fixes [#5077](https://github.com/influxdb/influxdb/issues/5077). Thanks @pires
+- [#5193](https://github.com/influxdata/influxdb/issues/5193): Missing data a minute before current time. Comes back later.
 
 ## v0.9.6 [2015-12-09]
 

tsdb/engine/tsm1/engine.go

@@ -815,7 +815,6 @@ func (c *devCursor) nextTSM() (int64, interface{}) {
 		if c.tsmPos >= len(c.tsmValues) {
 			c.tsmValues, _ = c.tsmKeyCursor.Next(c.ascending)
 			if len(c.tsmValues) == 0 {
-				c.tsmKeyCursor.Close()
 				return tsdb.EOF, nil
 			}
 			c.tsmPos = 0
@@ -826,7 +825,6 @@ func (c *devCursor) nextTSM() (int64, interface{}) {
 		if c.tsmPos < 0 {
 			c.tsmValues, _ = c.tsmKeyCursor.Next(c.ascending)
 			if len(c.tsmValues) == 0 {
-				c.tsmKeyCursor.Close()
 				return tsdb.EOF, nil
 			}
 			c.tsmPos = len(c.tsmValues) - 1