Right now, the .hgignore file doesn't ignore JTwork and JTreport directories that are generated at the root of the repository. For example, when I run the jtreg tests from the root of the repo and then issue a "hg st", I see:

...
? JTreport/html/config.html
? JTreport/html/env.html
? JTreport/html/error.html
? JTreport/html/error_gr.html
? JTreport/html/excluded.html
...
? JTwork/classes/0/java/net/httpclient/ALPNFailureTest.d/ALPNFailureTest$ReadOnlyServer.class
? JTwork/classes/0/java/net/httpclient/ALPNFailureTest.d/ALPNFailureTest.class
? JTwork/classes/0/java/net/httpclient/ALPNProxyFailureTest.d/ALPNFailureTest$ReadOnlyServer.class
? JTwork/classes/0/java/net/httpclient/ALPNProxyFailureTest.d/ALPNFailureTest.class

If however the jtreg tests are run from a sub-directory of the repo root, then the generated JTwork and JTreport sub-directories are correctly ignored.

It would be good to ignore these directories from the root of the repo too.

This enhancement is being raised after a discussion and suggestion in the jdk-dev list here https://mail.openjdk.java.net/pipermail/jdk-dev/2019-June/003076.html