Thank you!

• Use jexec_args variable with all parameters in both getopt calls.

• Add missing error handling for putenv(3).

In D54660#1249395, @jamie wrote:

Why does it matter that putenv(3) doesn't create a copy?

• Avoid memory allocations.
• Parse -e twice. Once to verify correctness. Again to set the variable.

Align putenv_copy() function declaration for consistency.

Since putenv(3) does not create a copy, I had to implement a function to emulate the old behavior, so now setenv(3) is used after parsing the environment variable.