fix bug #9786:

duplicate advancements from combination of [base_unit] and [advancefrom]

data/campaigns/Liberty/units/Villagers.cfg

@@ -29,7 +29,7 @@
     id=Bandit_Peasant
     name= _ "Village Elder"
     alignment=neutral
-    advanceto=Highwayman_Peasant
+    advanceto=null
     unit_description= _ "Each of the villages scattered across the Wesnoth countryside is normally guided by a group of elders, who are the village's wisest and most experienced residents."
 #ifdef CAMPAIGN_LIBERTY
 #else
@@ -45,6 +45,9 @@
     name= _ "Senior Village Elder"
     alignment=neutral
     hitpoints=67
+    [advancefrom]
+        unit=Bandit_Peasant
+    [/advancefrom]
     cost=66
     unit_description= _ "The entire village looks to the senior elder for guidance. Strong and wise, the senior elders take responsibility for the community's well-being on their shoulders. Provincial officials tend to choose senior village elders as magistrates so that legal and customary authority will coincide."
 #ifdef CAMPAIGN_LIBERTY
@@ -88,7 +91,7 @@
     name= _ "Watchman"
     alignment=neutral
     hitpoints=40
-    advanceto=Fugitive_Peasant
+    advanceto=null
     cost=40
     unit_description= _ "The watchmen are men and women who protect the villages from marauders, both human and otherwise, that prowl the Wesnoth countryside at night."
 #ifdef CAMPAIGN_LIBERTY
@@ -108,6 +111,9 @@
     name= _ "Borderer"
     alignment=neutral
     hitpoints=61
+    [advancefrom]
+        unit=Outlaw_Peasant
+    [/advancefrom]
     cost=80
     unit_description= _ "Each village has a group of highly capable fighters dedicated to fending off orc raids. Some of these join the Wesnoth army, while others join the core of the village's patrol."
 #ifdef CAMPAIGN_LIBERTY
@@ -148,7 +154,7 @@
     alignment=neutral
     experience=98
     cost=26
-    advanceto=Huntsman_Peasant,Human Ranger
+    advanceto=Human Ranger
     unit_description= _ "Trappers are skilled hunters who supply food and furs for several villages. Their hunting experience makes them most valuable at night and in forests and swamps."
 #ifdef CAMPAIGN_LIBERTY
 #else
@@ -164,6 +170,9 @@
     name= _ "Peasant Huntsman"
     alignment=neutral
     hitpoints=55
+    [advancefrom]
+        unit=Trapper_Peasant
+    [/advancefrom]
     cost=52
     unit_description= _ "Huntsmen have spent their lives in the backwoods and swamps of their wilderness homes. They can bullseye wamprats and track anything that moves in their territory."
 #ifdef CAMPAIGN_LIBERTY