You can

clean-all

then

./pants jar ...

and find:

$ tree .pants.d/jar/create/
.pants.d/jar/create/
└── 252d64521cf9
    ├── src.java.com.sun.tools.javac.api.api
    │   ├── 5c78e180e544
    │   │   └── api.jar
    │   └── current -> 5c78e180e544
    ├── src.java.org.pantsbuild.args4j.args4j
    │   ├── 3649d44e1ce2
    │   │   └── args4j.jar
    │   └── current -> 3649d44e1ce2
    ├── src.java.org.pantsbuild.junit.annotations.annotations
    │   ├── 94c1daade151
    │   │   └── annotations.jar
    │   └── current -> 94c1daade151
    ├── src.java.org.pantsbuild.testing.testing
    │   ├── 8bc92a4eec7c
    │   │   └── testing.jar
    │   └── current -> 8bc92a4eec7c
    ├── src.java.org.pantsbuild.tools.jar.jar
    │   ├── 012ebfce1e03
    │   │   └── jar.jar
    │   └── current -> 012ebfce1e03
    ├── src.java.org.pantsbuild.tools.junit.junit
    │   ├── 47e84656060d
    │   │   └── junit.jar
    │   └── current -> 47e84656060d
    ├── src.java.org.pantsbuild.tools.junit.withretry.withretry
    │   ├── 3ab833ffe2c1
    │   │   └── withretry.jar
    │   └── current -> 3ab833ffe2c1
    └── src.java.org.pantsbuild.tools.runner.runner-library
        ├── 84cd17ae0f83
        │   └── runner-library.jar
        └── current -> 84cd17ae0f83

25 directories, 8 files

But that's obviously way too low-level and is just a workaround.