Incompatible search for main files

[nicmcd]

Here is my py_binary rule:

py_binary(
    name = "testing",
    srcs = ["bin/testing.py"],
)

The py_binary rule finds the main file just fine even though it is in the bin directory. However, the following rule fails:

par_binary(
    name = "testing",
    srcs = ["bin/testing.py"],
)

I'm using Bazel version 0.26.1 and subpar 2.0.0