kas: add GIT_CREDENTIAL_HELPER environment variable

This allows to set a git credential helper in the .gitconfig, in order
to handle git authentications. For instance when bitbake recipes require
to clone from git via https.

Signed-off-by: Claudius Heine <ch@denx.de>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>

kas/libcmds.py

@@ -164,6 +164,11 @@ class SetupHome(Command):
             fds.write('[User]\n'
                       '\temail = kas@example.com\n'
                       '\tname = Kas User\n')
+            if os.environ.get('GIT_CREDENTIAL_HELPER', False):
+                fds.write('[credential]\n'
+                          '\thelper = '
+                          + os.environ.get('GIT_CREDENTIAL_HELPER')
+                          + '\n')
 
         if os.environ.get('AWS_CONFIG_FILE', False) \
                 and os.environ.get('AWS_SHARED_CREDENTIALS_FILE', False):