Bad command execution with Exec task, overwritten PATH environment variable, and TestKit

[v1nc3n4]

Hello,

Please find enclosed a demo project demonstrating an incorrect forwarding/usage of the PATH environment variable by the Gradle Runner/TestKit.
Project: gradle-exec.zip

Environment
O/S: Ubuntu 18.04.4 LTS
JDK: OpenJDK 1.8.0_242 64 bits
Gradle: 6.3

Description
The single test class in the project performs the following actions:

• Create 2 identical shell scripts with the same file name mycommand, that echoes their absolute path and the content of the PATH environment variable. Both scripts are created in 2 temporary directories whose name starts with bin1- prefix, respectively bin2- prefix.
• Create a build.gradle file with a myTask task based on the Exec type, that simply executes the mycommand command, relying on the PATH environment variable to locate it.
• Execute test shouldExecCommandInBin1: prepend the PATH environment variable with bin1-... directory, and provide this variable to the Gradle Runner. The expected result here is command bin1-.../ mycommand is executed, which is OK.
• Execute test shouldExecCommandInBin2: prepend the PATH environment variable with bin2-... directory, and provide this variable to the Gradle Runner. The expected result here is command bin2-.../mycommand is executed, which is KO. Indeed, even if the content of the PATH environment variable seems relevant once in the command shell script, the Gradle Runner executes the bin1-.../mycommand command.

Below you will find the output of a gradlew test command:

$ ./gradlew test
> Task :test
ExecPathTest > shouldRunTaskWithCommandInBin1() STANDARD_OUT
    > Task :myTask
    /tmp/bin1-8749809166213298195/mycommand: PATH=/tmp/bin1-8749809166213298195:...:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
    BUILD SUCCESSFUL
     in 6s
    1 actionable task: 1 executed
ExecPathTest > shouldRunTaskWithCommandInBin1() PASSED
ExecPathTest > shouldRunTaskWithCommandInBin2() STANDARD_OUT
    > Task :myTask
    /tmp/bin1-8749809166213298195/mycommand: PATH=/tmp/bin2-8177081762864333825:...:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
    BUILD SUCCESSFUL
     in 1s
    1 actionable task: 1 executed
ExecPathTest > shouldRunTaskWithCommandInBin2() PASSED
BUILD SUCCESSFUL in 14s
4 actionable tasks: 3 executed, 1 up-to-date

Maybe I made a mistake, but actually I don't understand why such result. It is also strange for me because the PATH environment variable is relevant once in the shell script.
Thanks in advance for your help!
BR,
Vincent