diff --git a/mercurial/revlogutils/docket.py b/mercurial/revlogutils/docket.py
--- a/mercurial/revlogutils/docket.py
+++ b/mercurial/revlogutils/docket.py
@@ -17,10 +17,16 @@
 
 from __future__ import absolute_import
 
+import errno
+import os
+import random
 import struct
 
 from .. import (
+    encoding,
     error,
+    node,
+    pycompat,
     util,
 )
 
@@ -28,6 +34,55 @@
     constants,
 )
 
+
+def make_uid(id_size=8):
+    """return a new unique identifier.
+
+    The identifier is random and composed of ascii characters."""
+    # size we "hex" the result we need half the number of bits to have a final
+    # uuid of size ID_SIZE
+    return node.hex(os.urandom(id_size // 2))
+
+
+# some special test logic to avoid anoying random output in the test
+stable_docket_file = encoding.environ.get(b'HGTEST_UUIDFILE')
+
+if stable_docket_file:
+
+    def make_uid(id_size=8):
+        try:
+            with open(stable_docket_file, mode='rb') as f:
+                seed = f.read().strip()
+        except IOError as inst:
+            if inst.errno != errno.ENOENT:
+                raise
+            seed = b'04'  # chosen by a fair dice roll. garanteed to be random
+        if pycompat.ispy3:
+            iter_seed = iter(seed)
+        else:
+            iter_seed = (ord(c) for c in seed)
+        # some basic circular sum hashing on 64 bits
+        int_seed = 0
+        low_mask = int('1' * 35, 2)
+        for i in iter_seed:
+            high_part = int_seed >> 35
+            low_part = (int_seed & low_mask) << 28
+            int_seed = high_part + low_part + i
+        r = random.Random()
+        if pycompat.ispy3:
+            r.seed(int_seed, version=1)
+        else:
+            r.seed(int_seed)
+        # once we drop python 3.8 support we can simply use r.randbytes
+        raw = r.getrandbits(id_size * 4)
+        assert id_size == 8
+        p = struct.pack('>L', raw)
+        new = node.hex(p)
+        with open(stable_docket_file, 'wb') as f:
+            f.write(new)
+        return new
+
+
 # Docket format
 #
 # * 4 bytes: revlog version
diff --git a/mercurial/revlogutils/nodemap.py b/mercurial/revlogutils/nodemap.py
--- a/mercurial/revlogutils/nodemap.py
+++ b/mercurial/revlogutils/nodemap.py
@@ -9,19 +9,16 @@
 from __future__ import absolute_import
 
 import errno
-import os
-import random
 import re
 import struct
 
 from ..node import hex
 
 from .. import (
-    encoding,
     error,
-    pycompat,
     util,
 )
+from . import docket as docket_mod
 
 
 class NodeMap(dict):
@@ -281,56 +278,6 @@
 S_VERSION = struct.Struct(">B")
 S_HEADER = struct.Struct(">BQQQQ")
 
-ID_SIZE = 8
-
-
-def _make_uid():
-    """return a new unique identifier.
-
-    The identifier is random and composed of ascii characters."""
-    # size we "hex" the result we need half the number of bits to have a final
-    # uuid of size ID_SIZE
-    return hex(os.urandom(ID_SIZE // 2))
-
-
-# some special test logic to avoid anoying random output in the test
-stable_docket_file = encoding.environ.get(b'HGTEST_DOCKETIDFILE')
-
-if stable_docket_file:
-
-    def _make_uid():
-        try:
-            with open(stable_docket_file, mode='rb') as f:
-                seed = f.read().strip()
-        except IOError as inst:
-            if inst.errno != errno.ENOENT:
-                raise
-            seed = b'4'  # chosen by a fair dice roll. garanteed to be random
-        if pycompat.ispy3:
-            iter_seed = iter(seed)
-        else:
-            iter_seed = (ord(c) for c in seed)
-        # some basic circular sum hashing on 64 bits
-        int_seed = 0
-        low_mask = int('1' * 35, 2)
-        for i in iter_seed:
-            high_part = int_seed >> 35
-            low_part = (int_seed & low_mask) << 28
-            int_seed = high_part + low_part + i
-        r = random.Random()
-        if pycompat.ispy3:
-            r.seed(int_seed, version=1)
-        else:
-            r.seed(int_seed)
-        # once we drop python 3.8 support we can simply use r.randbytes
-        raw = r.getrandbits(ID_SIZE * 4)
-        assert ID_SIZE == 8
-        p = struct.pack('>L', raw)
-        new = hex(p)
-        with open(stable_docket_file, 'wb') as f:
-            f.write(new)
-        return new
-
 
 class NodeMapDocket(object):
     """metadata associated with persistent nodemap data
@@ -340,7 +287,7 @@
 
     def __init__(self, uid=None):
         if uid is None:
-            uid = _make_uid()
+            uid = docket_mod.make_uid()
         # a unique identifier for the data file:
         #   - When new data are appended, it is preserved.
         #   - When a new data file is created, a new identifier is generated.
diff --git a/tests/run-tests.py b/tests/run-tests.py
--- a/tests/run-tests.py
+++ b/tests/run-tests.py
@@ -1386,8 +1386,8 @@
         env['PYTHONUSERBASE'] = sysconfig.get_config_var('userbase') or ''
         env['HGEMITWARNINGS'] = '1'
         env['TESTTMP'] = _bytes2sys(self._testtmp)
-        docket_id_file = os.path.join(_bytes2sys(self._testtmp), 'DOCKETID')
-        env['HGTEST_DOCKETIDFILE'] = docket_id_file
+        uid_file = os.path.join(_bytes2sys(self._testtmp), 'UID')
+        env['HGTEST_UUIDFILE'] = uid_file
         env['TESTNAME'] = self.name
         env['HOME'] = _bytes2sys(self._testtmp)
         if os.name == 'nt':