test: Activate all regtest softforks at height 1, unless overridden

test/functional/feature_dersig.py

@@ -8,7 +8,6 @@ Test the DERSIG soft-fork activation on regtest.
 """
 
 from test_framework.blocktools import (
-    DERSIG_HEIGHT,
     create_block,
     create_coinbase,
 )
@@ -42,10 +41,14 @@ def unDERify(tx):
     tx.vin[0].scriptSig = CScript(newscript)
 
 
+DERSIG_HEIGHT = 102
+
+
 class BIP66Test(BitcoinTestFramework):
     def set_test_params(self):
         self.num_nodes = 1
         self.extra_args = [[
+            f'-testactivationheight=dersig@{DERSIG_HEIGHT}',
             '-whitelist=noban@127.0.0.1',
             '-par=1',  # Use only one script thread to get the exact log msg for testing
         ]]