While trying to delete a wrongly added restriction (no_u_turn) in iD, through the TR window, ended up creating a new restriction (only_u_turn) in addition to deleting the old one without any visible warnings.

osm Change file:
<?xml version="1.0" encoding="UTF-8"?>
<osmChange version="0.6" generator="iD">
<create>
<relation id="-8" version="0">
<member type="way" role="from" ref="417310791" />
<member type="way" role="via" ref="573973104" />
<member type="way" role="to" ref="573973107" />
<tag k="type" v="restriction" />
<tag k="restriction" v="only_u_turn" />
</relation>
</create>
<modify />
<delete if-unused="true">
<relation id="8155829" version="1">
<member type="way" role="from" ref="417310791" />
<member type="way" role="via" ref="573973104" />
<member type="way" role="to" ref="573973107" />
<tag k="restriction" v="no_u_turn" />
<tag k="type" v="restriction" />
</relation>
</delete>
</osmChange>
Thanks for reporting @abhisheksaikia - I noticed in the screenshot that the turn arrow didn't even turn blue (only_u_turn). Maybe the bug happens when the user can clicks _very_ fast - is this what you did?
I'll check the code and try to reproduce the issue - we might have to block clicks until the graph update has caught up..
@bhousel
no_left and no_u turn-restrictionno_left - first click it changes to only_left (blue) and second click deletes the TR.no_u - the first click (in single action) both only_u and deletion is happening (no visible change in colors). (_in gif you can notice, deletion of no_u doesn't change to blue but directly deletes but doesn't give indication of TR creation_)
Follow the steps as per to reproduce the problem

Awesome thanks @srividyacb and @abhisheksaikia for the detailed report 馃憤
Thanks this is fixed now..
The issue was that we were only allowing the only_ to go in one direction along the bidirectional connecting road. (I guess I was thinking about oneways the day I wrote that code).
Deleting the no_u restriction would cycle to an only_u restriction, but this restriction was ignored because of the bug, causing the turn arrow to turn green (even though that only_u was silently created).
Most helpful comment
Awesome thanks @srividyacb and @abhisheksaikia for the detailed report 馃憤