How to change target directory of an external command in a Python script

Good morning,
I am writing a Python script for comparing two installers. Therefore I am using "sfk" (Swiss File Knife) technology for browsing through the unzipped directories, including browsing inside *.jar files).
My script looks as follows:

  cmd_sfk1 = "sfk list -hidden -arc -time -size -tofile content_dir1.txt " + lv_inst_dir1
  cmd_sfk2 = "sfk list -hidden -arc -time -size -tofile content_dir2.txt " + lv_inst_dir2

  try:
    subprocess.call(cmd_sfk1)
  except Exception as ex:
    ...

  try:
    subprocess.call(cmd_sfk2)
  except Exception as ex:
    ...

As you can see, the results are written in two files (content_dir1.txt) and (content_dir2.txt), and it's the idea that a simple file comparison gives me the difference between both directories/file tree.

However, this is not working as the name of the directory is included in the file, here's an excerpt:

...
2015-09-29 14:04:20          119 Dir1\InstallerData\...\MediaId.properties
2015-09-29 14:00:08          357 Dir1\InstallerData\...\\my.ini
...

The presence of "Dir1" in that file messes up the comparison.

I see one "simple" solution: modifying the target directory of the commands, something like:

  cmd_sfk1 = "sfk list -hidden -arc -time -size -tofile ../content_dir1.txt " + "."
  cmd_sfk2 = "sfk list -hidden -arc -time -size -tofile ../content_dir2.txt " + "."

  try:
    subprocess.call(cmd_sfk1, target_directory=lv_inst_dir1)
  except Exception as ex:
    ...

  try:
    subprocess.call(cmd_sfk2, target_directory=lv_inst_dir2)
  except Exception as ex:
    ...

(a bit like "pushd" and "popd" in DOS batch-files)
The intention is to end up with following content_dir1.txt content:

...
2015-09-29 14:04:20          119 InstallerData\...\MediaId.properties
2015-09-29 14:00:08          357 InstallerData\...\\my.ini
...

(without "Dir1")
And now my question: does anybody know how to modify the target directory of a subprocess in Python?

Thanks
Dominique