Support installing setuptools from .tar.gz

In addition to already supported .zip archives

slapos/rebootstrap/bootstrap.py

-import os, sys
+import errno, os, sys
 
 class FakeSysExecutable(object):
 
@@ -36,15 +36,21 @@ def setup_script(path, python=sys.executable):
     easy_install.sys = sys
 
 def main():
-  import shutil, subprocess, tempfile, zipfile
+  import shutil, subprocess, tarfile, tempfile, zipfile
   eggs_dir = sys.argv[2]
   cache = sys.argv[3]
+  base = os.path.join(cache, sys.argv[4].replace('==', '-'))
   # Install setuptools.
-  src = os.path.join(cache, sys.argv[4].replace('==', '-') + '.zip')
   tmp = tempfile.mkdtemp()
   try:
-    with zipfile.ZipFile(src) as zip_file:
-      zip_file.extractall(tmp)
+    try:
+      with zipfile.ZipFile(base + '.zip') as zip_file:
+        zip_file.extractall(tmp)
+    except IOError as e:
+      if e.errno != errno.ENOENT:
+        raise
+      with tarfile.open(base + '.tar.gz') as tar_file:
+        tar_file.extractall(tmp)
     src, = os.listdir(tmp)
     subprocess.check_call((sys.executable, 'setup.py', '-q', 'bdist_egg',
                           '--dist-dir', tmp), cwd=os.path.join(tmp, src))