config: Fallback to configparser if configobj is missing

This commit allows fallback to python standard configparser in case
configobj package is not installed.

This allows `west config` to work with existing bootstrappers.

Having the fallback mechanism in an independent commit allows to easily
rollback the commit when it is considered that all has configobj as
part of west installation.

Signed-off-by: Torsten Rasmussen <torsten.rasmussen@nordicsemi.no>

src/west/configuration.py

@@ -7,10 +7,16 @@ Configuration file handling, using the standard configparser module.
 '''
 
 import configparser
-import configobj
 import os
 import platform
 from enum import Enum
+try:
+    # Try to import configobj.
+    # If not available we fallback to simple configparser
+    import configobj
+    use_configobj = True
+except ImportError:
+    use_configobj = False
 
 from west.util import west_dir
 
@@ -121,13 +127,22 @@ def update_config(section, key, value, configfile=ConfigFile.LOCAL):
         filename = os.path.join(west_dir(), configfile.value)
     else:
         filename = configfile.value
-    updater = configobj.ConfigObj(filename)
+
+    if use_configobj:
+        updater = configobj.ConfigObj(filename)
+    else:
+        updater = configparser.ConfigParser()
+        read_config(configfile, updater)
 
     if section not in updater:
         updater[section] = {}
     updater[section][key] = value
 
-    updater.write()
+    if use_configobj:
+        updater.write()
+    else:
+        with open(filename, 'w') as f:
+            updater.write(f)
 
 
 def use_colors():