Bun Shell doesn't seem to search PATH correctly

[DanielBaulig]

What version of Bun is running?

1.0.35

What platform is your computer?

Linux 5.15.146.1-microsoft-standard-WSL2 x86_64 unknown

What steps can reproduce the bug?

Create index.ts

import { $ } from 'bun';

await $`mkdir -p .mypath && echo '#!/bin/sh' > .mypath/prog && chmod a+x .mypath/prog && prog`.env({PATH: `.mypath:${process.env.PATH}`});

Run it

# bun index.ts
bun: command not found: prog

Try running equivalent from any shell:

# PATH=".mypath:$PATH" sh -c 'mkdir -p .mypath && echo ''#!/bin/sh'' > .mypath/prog && chmod a+x .mypath/prog && prog'
# 

What is the expected behavior?

Bun Shell should find and run prog

What do you see instead?

Bun Shell doesn't find prog, even though it's in the PATH for the Shell context.

Additional information

Note: the example can be more simple. For completeness sake I've included all the steps into a single command line. It seems like any executable file in any location will not be found by Bun Shell if that location was added to the Bun Shell environment PATH variable after bun startup, either locally or globally. (i.e. $`...`.env() or $.env()). Using an absolute path, a non-hidden path or adding the location to the end of PATH doesn't make a difference either. It's almost as if Bun Shell's search path is set upon bun execution and not updated by any calls to .env.

Changing the PATH variable before bun invocation resolves the issue, e.g.

PATH=".mypath:$PATH" bun index.ts