Regression test hphp/test/slow/ext_vsdebug/conditional_bp.php fails consistently

### HHVM Version

hphp/hhvm/hhvm --version
HipHop VM 3.28.0-dev (rel)
Compiler: heads/master-0-g321e7e633327434d5d79dbc1f6f119f3c0b79d10
Repo schema: fbff5d960613e0ede87d1b2b17c518697f2c3e9d

### Operating System and Version

ubuntu 16.04
uname -a
Linux lab-3 4.2.0 #1 SMP Wed Nov 25 14:00:54 CST 2015 aarch64 aarch64 aarch64 GNU/Linux

### Standalone code, or other way to reproduce the problem

hphp/test/run hphp/test/slow/ext_vsdebug/conditional_bp.php

### Actual result

hphp/test/run hphp/test/slow/ext_vsdebug/conditional_bp.php
Running 1 tests in 1 threads (0 in serial)

FAILED: hphp/test/slow/ext_vsdebug/conditional_bp.php
001+ Fatal error: Uncaught exception 'UnexpectedValueException' with message 'Hit a php exception : Error: A semicolon (';') !== Hit fatal : A semicolon (';') is expected here.' in /data2/swalk/play.081518a/hhvm/hphp/test/slow/ext_vsdebug/conditional_bp.php:34
001- OK!
002+ Stack trace:
003+ #0 {main}

### Expected result

pass

Checking testing history for last month, it's been failing since the test of August 7th,
all option variants similar to interpreter above.

play.080318a/hhvm/bad.080318a
play.080618a/hhvm/bad.080618a
play.080718a/hhvm/bad.080718a
7:hphp/test/slow/ext_vsdebug/conditional_bp.php | F | F | F | F | F | F |
play.080818a/hhvm/bad.080818a
7:hphp/test/slow/ext_vsdebug/conditional_bp.php | F | F | F | F | F | F |
play.080918a/hhvm/bad.080918a
6:hphp/test/slow/ext_vsdebug/conditional_bp.php | F | F | F | F | F | F |
play.081018a/hhvm/bad.081018a
7:hphp/test/slow/ext_vsdebug/conditional_bp.php | F | F | F | F | F | F |
play.081318a/hhvm/bad.081318a
8:hphp/test/slow/ext_vsdebug/conditional_bp.php | F | F | F | F | F | F |
play.081418a/hhvm/bad.081418a
6:hphp/test/slow/ext_vsdebug/conditional_bp.php | F | F | F | F | F | F |
play.081518a/hhvm/bad.081518a
5:hphp/test/slow/ext_vsdebug/conditional_bp.php | F | F | F | F | F | F |

Traced to this checkin

commit eaafa8defb32ca725a07364fff80f5e4935d3127
Author: Eric Bluestein
Date: Mon Aug 6 15:57:54 2018 -0700

HHVM Debugger: fix and re-enable VSP debugger regression tests