yooml/cgpsync: cgpsync.go; 20 LoC

Found a possible issue in [yooml/cgpsync](https://www.github.com/yooml/cgpsync) at [cgpsync.go](https://github.com/yooml/cgpsync/blob/436fbd7b582596456a364f988b7f7661cae6bd15/cgpsync.go#L226-L245)

Below is the message reported by the analyzer for this snippet of code. Beware that the analyzer only reports the first
issue it finds, so please do not limit your consideration to the contents of the below message.

> range-loop variable i used in defer or goroutine at line 231

[Click here to see the code in its original context.](https://github.com/yooml/cgpsync/blob/436fbd7b582596456a364f988b7f7661cae6bd15/cgpsync.go#L226-L245)

Click here to show the 20 line(s) of Go which triggered the analyzer.

```go
for i :=range ch3{
ch4:=make(chan string,1)
sql_copyfrom:=fmt.Sprintf("copy %s from '/tmp/cgpsync/%d.pipe';",i.child_tbl_name,m)

go func() {
log.Println("开始同步表：",i.table_name,".",i.child_tbl_name)
copy_from(sql_copyfrom,i.child_tbl_name,ch4,i.table_name,db)
}()

echo:=fmt.Sprintf("psql -h %s -p %d -U %s -d %s -c 'copy %s to stdout' > /tmp/cgpsync/%d.pipe",
dbconfig.GetString("host"), dbconfig.GetInt("port"), dbconfig.GetString("user"), dbconfig.GetString("dbname"),i.child_tbl_name,m)
py :=exec.Command("/bin/bash","-c",echo)
stderr := &bytes.Buffer{}
py.Stderr = stderr
if err := py.Run(); err != nil {
fmt.Println("Error: ", err, "|", stderr.String())
}
<-ch4
ch2<-i.child_tbl_name
}

```

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commit ID: 436fbd7b582596456a364f988b7f7661cae6bd15