bug#26491: date and echo using with underscore

[Edmond Yuen]

Please verify the script below:

#/bin/bash

D=`date +%Y%m%d`
i="someparameter"

echo $D_$i
echo $D\_$i
echo $D
echo $i
echo _




//   my system is debian with coreutils 8.26-3
//
//   db=`date -d "-1day" +%Y%m%d`
//   i="0"
This is the result from my system

~$ echo "$db_$i"
0
~$ echo "$db\_$i"
20170413\_0
~$ echo "$db$i"
201704130

Thank you!