combine server environment vars with explicitly set vars

[patrickjahns]

Addresses CI failures

[phil-davis]

Note: the problem was that the PHP proc_open() $env parameter is the only environment variables that the process receives, it is NOT bonus environment variables on top of what it would have by default. My bad for not realizing this.

The particular symptom was that when the testing app runs an occ command for us, the child process has only the few environment variable(s) (or none) that we explicitly passed. Some apps have code that checks for the environment variable CI an that should have come from the general system environment on drone, but it went AWOL.

[patrickjahns]

Still suffering from the Problem that E in the variable order needs to be defined to check $_ENV var.

http://de2.php.net/manual/en/reserved.variables.environment.php#98113