Variable declaration on the first line of .env ignored

[rcotta]

Describe the bug

When using a .env file with podman-compose, environment variables defined on the first line of the file are not expanded in docker-compose.yml.
If a dummy first line (comment or another variable declaration) is added, the variables are expanded correctly.

IMPORTANT: if you try reproduce the steps below but, this time, adding a dummy first line to the .env file, then it behaves as expected.

Steps to reproduce the behavior:

1. Create a .env file with the following contents:

VAR1=value1
VAR2=value2

2. Create a docker-compose.yml with the following contents:

services:

  my-service:
    image: mongo:6.0
    args:
      - arg1=${VAR1}
      - arg2=${VAR2}
    restart: unless-stopped

3. run podman-compose config

Expected behavior
VAR1 value should be expanded.

Actual behavior

VAR1 is not expanded.

Output

services:
  my-service:
    args:
    - arg1=
    - arg2=value2
    image: mongo:6.0
    restart: unless-stopped

$ podman-compose version
podman-compose version 1.5.0
podman version 5.5.2

$ podman version
Client:       Podman Engine
Version:      5.5.2
API Version:  5.5.2
Go Version:   go1.24.4
Git Commit:   e7d8226745ba07a64b7176a7f128e4ef53225a0e
Built:        Tue Jun 24 13:13:04 2025
OS/Arch:      windows/amd64

Server:       Podman Engine
Version:      5.6.1
API Version:  5.6.1
Go Version:   go1.24.6
Git Commit:   1e2b2315150b2ffa0971596fb5da8cd83f3ce0e1
Built:        Wed Sep  3 21:00:00 2025
OS/Arch:      linux/amd64
...

[coillteoir]

I tried reproducing this, it may have been fixed