Is this a bug? ZBREAK Trace option does not appear to handle comma-separated SET command

I came across this behaviour when debugging some Cache ObjectScript code.  I have provided a simple example below.

Example 1:

START
 ZBREAK /TRACE:ON:"C:/temp/zbreak_trace.log"
 ZBREAK *VAR1:"T"
 ZBREAK *VAR2:"T"
 ZBREAK *VAR3:"T"
 Set (VAR1,VAR2,VAR3)=""
 Kill VAR1,VAR2,VAR3
 Quit

Trace Output:

Trace: ZBREAK SET VAR3="" at START+5^TRACE

Trace: ZBREAK KILL VAR1 at START+6^TRACE

Trace: ZBREAK KILL VAR2 at START+6^TRACE

Trace: ZBREAK KILL VAR3 at START+6^TRACE

$ZV value:

Cache for Windows (x86-32) 2017.1 (Build 792) Mon Mar 20 2017 20:20:07 EDT

Notice that the SET statement in the log file only refers to VAR3 - the last variable that was initialised to empty string. Here are a couple of ways to mitigate this issue.

1. Do not use the ZBREAK Trace option. Use watchpoints in your preferred IDE. 
2. Write all SET statements in long-hand format. Avoid the round-brackets comma syntax.

Example 2:

START
 ZBREAK /TRACE:ON:"C:/temp/zbreak_trace.log"
 ZBREAK *VAR1:"T"
 ZBREAK *VAR2:"T"
 ZBREAK *VAR3:"T"
 Set VAR1=""
 Set VAR2=""
 Set VAR3=""
 Kill VAR1,VAR2,VAR3
 Quit

Trace Output:

Trace: ZBREAK SET VAR1="" at START+5^TRACE

Trace: ZBREAK SET VAR2="" at START+6^TRACE

Trace: ZBREAK SET VAR3="" at START+7^TRACE

Trace: ZBREAK KILL VAR1 at START+8^TRACE

Trace: ZBREAK KILL VAR2 at START+8^TRACE

Trace: ZBREAK KILL VAR3 at START+8^TRACE

Notice that the SET statements now feature all three variables as expected.