Searching a regex of the form (and|the) causes error

[rashmi18]

When you hit '/' to enter search mode, and if you type '()' and try going back within the parentheses to type the regex. Tab hangs and it does not allow you to move the cursor backwards.

https://screenshot.googleplex.com/F1onvrJCJYV

[ewen-goisot]

Still true / almost the same problem now:
if I type « ab| » the result is «a|b» with no bug,
but if I directly type «a|», the tab freeze before I can type «b».
Also true if I type «a*b» : no time to type «b».
I think it's something like «if the empty string is valid, then freeze».
.
I also noticed that if I stop typing anything in regex search bar, after a few seconds it stops consuming my CPU, as expected.
But if I simply move the cursor (arrow keys), it consumes CPU for nothing.