siggen: Drop non-multiconfig aware siggen support

diff --git a/lib/bb/runqueue.py b/lib/bb/runqueue.py
index cc36b84781..7451e5c56b 100644
--- a/lib/bb/runqueue.py
+++ b/lib/bb/runqueue.py
@@ -1245,9 +1245,8 @@  class RunQueueData:
         return len(self.runtaskentries)
 
     def prepare_task_hash(self, tid):
-        dc = bb.parse.siggen.get_data_caches(self.dataCaches, mc_from_tid(tid))
-        bb.parse.siggen.prep_taskhash(tid, self.runtaskentries[tid].depends, dc)
-        self.runtaskentries[tid].hash = bb.parse.siggen.get_taskhash(tid, self.runtaskentries[tid].depends, dc)
+        bb.parse.siggen.prep_taskhash(tid, self.runtaskentries[tid].depends, self.dataCaches)
+        self.runtaskentries[tid].hash = bb.parse.siggen.get_taskhash(tid, self.runtaskentries[tid].depends, self.dataCaches)
         self.runtaskentries[tid].unihash = bb.parse.siggen.get_unihash(tid)
 
     def dump_data(self):
@@ -2434,8 +2433,7 @@  class RunQueueExecute:
                 if self.rqdata.runtaskentries[p].depends and not self.rqdata.runtaskentries[tid].depends.isdisjoint(total):
                     continue
                 orighash = self.rqdata.runtaskentries[tid].hash
-                dc = bb.parse.siggen.get_data_caches(self.rqdata.dataCaches, mc_from_tid(tid))
-                newhash = bb.parse.siggen.get_taskhash(tid, self.rqdata.runtaskentries[tid].depends, dc)
+                newhash = bb.parse.siggen.get_taskhash(tid, self.rqdata.runtaskentries[tid].depends, self.rqdata.dataCaches)
                 origuni = self.rqdata.runtaskentries[tid].unihash
                 newuni = bb.parse.siggen.get_unihash(tid)
                 # FIXME, need to check it can come from sstate at all for determinism?
diff --git a/lib/bb/siggen.py b/lib/bb/siggen.py
index 3731cd6b69..be56b3a31c 100644
--- a/lib/bb/siggen.py
+++ b/lib/bb/siggen.py
@@ -53,11 +53,6 @@  class SignatureGenerator(object):
     """
     name = "noop"
 
-    # If the derived class supports multiconfig datacaches, set this to True
-    # The default is False for backward compatibility with derived signature
-    # generators that do not understand multiconfig caches
-    supports_multiconfig_datacaches = False
-
     def __init__(self, data):
         self.basehash = {}
         self.taskhash = {}
@@ -128,38 +123,6 @@  class SignatureGenerator(object):
     def set_setscene_tasks(self, setscene_tasks):
         return
 
-    @classmethod
-    def get_data_caches(cls, dataCaches, mc):
-        """
-        This function returns the datacaches that should be passed to signature
-        generator functions. If the signature generator supports multiconfig
-        caches, the entire dictionary of data caches is sent, otherwise a
-        special proxy is sent that support both index access to all
-        multiconfigs, and also direct access for the default multiconfig.
-
-        The proxy class allows code in this class itself to always use
-        multiconfig aware code (to ease maintenance), but derived classes that
-        are unaware of multiconfig data caches can still access the default
-        multiconfig as expected.
-
-        Do not override this function in derived classes; it will be removed in
-        the future when support for multiconfig data caches is mandatory
-        """
-        class DataCacheProxy(object):
-            def __init__(self):
-                pass
-
-            def __getitem__(self, key):
-                return dataCaches[key]
-
-            def __getattr__(self, name):
-                return getattr(dataCaches[mc], name)
-
-        if cls.supports_multiconfig_datacaches:
-            return dataCaches
-
-        return DataCacheProxy()
-
     def exit(self):
         return
 
@@ -298,11 +261,6 @@  class SignatureGeneratorBasic(SignatureGenerator):
         for dep in sorted(deps, key=clean_basepath):
             (depmc, _, _, depmcfn) = bb.runqueue.split_tid_mcfn(dep)
             depname = dataCaches[depmc].pkg_fn[depmcfn]
-            if not self.supports_multiconfig_datacaches and mc != depmc:
-                # If the signature generator doesn't understand multiconfig
-                # data caches, any dependency not in the same multiconfig must
-                # be skipped for backward compatibility
-                continue
             if not self.rundep_check(fn, recipename, task, dep, depname, dataCaches):
                 continue
             if dep not in self.taskhash:
@@ -726,13 +684,6 @@  class SignatureGeneratorTestEquivHash(SignatureGeneratorUniHashMixIn, SignatureG
         self.server = data.getVar('BB_HASHSERVE')
         self.method = "sstate_output_hash"
 
-#
-# Dummy class used for bitbake-selftest
-#
-class SignatureGeneratorTestMulticonfigDepends(SignatureGeneratorBasicHash):
-    name = "TestMulticonfigDepends"
-    supports_multiconfig_datacaches = True
-
 def dump_this_task(outfile, d):
     import bb.parse
     fn = d.getVar("BB_FILENAME")
diff --git a/lib/bb/tests/runqueue.py b/lib/bb/tests/runqueue.py
index 061a5a1f80..cc87e8d6a8 100644
--- a/lib/bb/tests/runqueue.py
+++ b/lib/bb/tests/runqueue.py
@@ -288,7 +288,7 @@  class RunQueueTests(unittest.TestCase):
         with tempfile.TemporaryDirectory(prefix="runqueuetest") as tempdir:
             extraenv = {
                 "BBMULTICONFIG" : "mc-1 mc_2",
-                "BB_SIGNATURE_HANDLER" : "TestMulticonfigDepends",
+                "BB_SIGNATURE_HANDLER" : "basichash",
                 "EXTRA_BBFILES": "${COREBASE}/recipes/fails-mc/*.bb",
             }
             tasks = self.run_bitbakecmd(["bitbake", "mc:mc-1:f1"], tempdir, "", extraenv=extraenv, cleanup=True)