Expose ENV variable to build environment for build step

[agjohnson]

Expose the current build step to the build environments. This would allow for step detection and executing commands during specific build steps.

On starting to execute the command, we'll post a new command to the API, then post command execution we finally PUT to the created command.

There are two uses for this:

• Streaming output: which I don't care about much
• Showing the command that is currently executing so that in the cases where the build fails due to timeout/memory/generic failure, the user sees the command that it failed on.

[humitos]

@agjohnson can you explain this issue a little more?

BTW, is this issue still relevant?

[agjohnson]

Updated the description. I think this is probably a valid feature, but low priority

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[humitos]

Closing as duplicated of #4288