tools/javac/modules/SourceInSymlinkTest.java fails when the jtreg workdir is set to be on drive that has been created using subst.

----------System.err:(40/2364)*----------
test: testModuleSourcePath
[DIRECT]:
testModuleSourcePath\\src\\m\\p\\A.java:1: error: not in a module on the module source path
package p; public class A{}
^
1 error
Exception running test testModuleSourcePath: toolbox.Task$TaskError: Task javac failed: rc=1
toolbox.Task$TaskError: Task javac failed: rc=1
at toolbox.AbstractTask.checkExit(AbstractTask.java:112)
at toolbox.JavacTask.run(JavacTask.java:306)
at SourceInSymlinkTest.testModuleSourcePath(SourceInSymlinkTest.java:87)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:563)
at toolbox.TestRunner.runTests(TestRunner.java:89)
at ModuleTestBase.runTests(ModuleTestBase.java:49)
at SourceInSymlinkTest.main(SourceInSymlinkTest.java:47)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:563)
at com.sun.javatest.regtest.agent.MainActionHelper$SameVMRunnable.run(MainActionHelper.java:230)
at java.base/java.lang.Thread.run(Thread.java:844)

1 errors
java.lang.Exception: 1 errors found
at toolbox.TestRunner.runTests(TestRunner.java:116)
at ModuleTestBase.runTests(ModuleTestBase.java:49)
at SourceInSymlinkTest.main(SourceInSymlinkTest.java:47)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:563)
at com.sun.javatest.regtest.agent.MainActionHelper$SameVMRunnable.run(MainActionHelper.java:230)
at java.base/java.lang.Thread.run(Thread.java:844)

JavaTest Message: Test threw exception: java.lang.Exception
JavaTest Message: shutting down test

result: Failed. Execution failed: `main' threw exception: java.lang.Exception: 1 errors found