From the Windows command prompt you can find out which program is being run from a command by using the 'where' command.

C:\Users\Lotus1>where perl
C:\Strawberry\perl\bin\perl.exe

C:\Users\Lotus1>where test1
C:\Users\Lotus1\test1.bat
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I found ant.bat at https://github.com/apache/ant/blob/master/src/script/ant.bat. I noticed this interesting comment at line 188:

:end
rem bug ID 32069: resetting an undefined env variable changes the erro
+rlevel.
if not "%_JAVACMD%"=="" set _JAVACMD=
if not "%_ANT_CMD_LINE_ARGS%"=="" set ANT_CMD_LINE_ARGS=

if "%ANT_ERROR%"=="0" goto mainEnd

goto omega
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The issue you are seeing is not a Perl bug but something that ant.bat is doing to the ERRORLEVEL. I don't know if the bug mentioned above is the source of the problem. Looking at bat files is too annoying so I'm giving up on it. Good luck.

Update: I found a bugreport for this issue with ant.bat. https://bz.apache.org/bugzilla/show_bug.cgi?id=41039 Which version of ant.bat are you using?