settings: Add the 'rebase-merge' setting to VCS base form and VCS settings model.

rhodecode/model/forms.py

@@ -382,6 +382,7 b' class _BaseVcsSettingsForm(formencode.Sc'
 
     rhodecode_pr_merge_enabled = v.StringBoolean(if_missing=False)
     rhodecode_use_outdated_comments = v.StringBoolean(if_missing=False)
+    rhodecode_hg_use_rebase_for_merging = v.StringBoolean(if_missing=False)
 
 
 def ApplicationUiSettingsForm():

rhodecode/model/settings.py

@@ -401,7 +401,9 b' class IssueTrackerSettingsModel(object):'
 class VcsSettingsModel(object):
 
     INHERIT_SETTINGS = 'inherit_vcs_settings'
-    GENERAL_SETTINGS = ('use_outdated_comments', 'pr_merge_enabled')
+    GENERAL_SETTINGS = (
+        'use_outdated_comments', 'pr_merge_enabled',
+        'hg_use_rebase_for_merging')
     HOOKS_SETTINGS = (
         ('hooks', 'changegroup.repo_size'),
         ('hooks', 'changegroup.push_logger'),