Refactor python function to create commandline arguments

[larsbergstrom]

In #331, we added a function to create the path string, make_cd_string:
https://github.com/servo/saltfs/blob/master/buildbot/master/files/config/factories.py#L118-L119

However, this could be cleaner! As seen in https://github.com/servo/saltfs/blob/master/buildbot/master/files/config/factories.py#L126-L127, there are more arguments in the array that are static.

In this fix, please rename the function and make it return an array with all of the arguments required, while still taking the same single argument (the command to execute).

[ashrwin]

Are you suggesting something like this ?

def make_cd_command(command):
    return ["bash", "-l", "-c", "cd /c/buildbot/slave/windows/build ; " + command ]

windows = ServoFactory([
    # TODO: convert this to use DynamicServoFactory
    # We need to run each command in a bash login shell, which breaks the
    # heuristics used by DynamicServoFactory.make_step
    steps.Compile(command= make_cd_command("./mach build -d -v"),
                  env=envs.build_windows),
    steps.Compile(command= make_cd_command("./mach test-unit"),
                  env=envs.build_windows),

    # TODO: run lockfile_changed.sh and manifest_changed.sh scripts
])

[aneeshusa]

@ashrko619 Yes, that's the right direction. If you open a PR I have a few style nits, but it looks good otherwise.

[ashrwin]

@aneeshusa Thanks, I will open a PR, btw what are the style nits here ?

[aneeshusa]

Here, we need to rename the make_cd_command function to reflect its updated scope, and there are some extra spaces.

Generally, I prefer to do reviewing on PRs because inline comments are clearer, so go ahead and open a PR and I'll make any future comments there.

[aneeshusa]

Fixed by #342.