ADDITIONAL SYSTEM INFORMATION :
Windows 10.0.17134.48
cmd + PowerShell 5.1.17134.48

openjdk 12-ea 2019-03-19
OpenJDK Runtime Environment 19.3 (build 12-ea+9)
OpenJDK 64-Bit Server VM 19.3 (build 12-ea+9, mixed mode)


A DESCRIPTION OF THE PROBLEM :
Please follow the steps to reproduce to see what I mean. Because editing the first line causes visual bugs, editing a multi-line command becomes very burdensome.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
open a shell window (the issue exists with both cmd.exe and powershell.exe) and run jshell:
* paste the following command (don't hit Enter yet)
var a = "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
* hit Home, move to the beginning of the String, and hit 'b'
-> 'b' appears, but the second line hasn't changed (since I added a character on the first line, the 'a' at the end should have shifted to the second line)
* hit 'b' again
-> nothing visually changes
* hit Enter
-> the result of the command is correct: 2 'b' characters were added at the beginning of the String
* hit the Up arrow and hit Home
-> the cursor is in front of 'var'
* hit Delete 3 times
-> the beginning of the line is now: jshel a = "...
* hit Enter
-> despite the visual bugs, the result is correct: hitting Delete 3 times simply removed 'var' from the command