diff --git a/mercurial/changelog.py b/mercurial/changelog.py
--- a/mercurial/changelog.py
+++ b/mercurial/changelog.py
@@ -263,6 +263,12 @@ class changelog(revlog.revlog):
             # changelogs don't benefit from generaldelta
             self.version &= ~revlog.REVLOGGENERALDELTA
             self._generaldelta = False
+
+        # Delta chains for changelogs tend to be very small because entries
+        # tend to be small and don't delta well with each. So disable delta
+        # chains.
+        self._storedeltachains = False
+
         self._realopener = opener
         self._delayed = False
         self._delaybuf = None
diff --git a/tests/test-acl.t b/tests/test-acl.t
--- a/tests/test-acl.t
+++ b/tests/test-acl.t
@@ -1509,7 +1509,7 @@ No branch acls specified
   acl: branch access granted: "e8fc755d4d82" on branch "foobar"
   acl: path access granted: "e8fc755d4d82"
   updating the branch cache
-  bundle2-input-part: total payload size 2101
+  bundle2-input-part: total payload size 2139
   bundle2-input-part: "pushkey" (params: 4 mandatory) supported
   pushing key for "phases:911600dab2ae7a9baff75958b84fe606851ce955"
   bundle2-input-part: "pushkey" (params: 4 mandatory) supported
@@ -1595,7 +1595,7 @@ Branch acl deny test
   acl: branch access granted: "911600dab2ae" on branch "default"
   acl: path access granted: "911600dab2ae"
   error: pretxnchangegroup.acl hook failed: acl: user "astro" denied on branch "foobar" (changeset "e8fc755d4d82")
-  bundle2-input-part: total payload size 2101
+  bundle2-input-part: total payload size 2139
   bundle2-input-bundle: 4 parts total
   transaction abort!
   rollback completed
@@ -1663,7 +1663,7 @@ Branch acl empty allow test
   acl: acl.allow not enabled
   acl: acl.deny not enabled
   error: pretxnchangegroup.acl hook failed: acl: user "astro" not allowed on branch "default" (changeset "ef1ea85a6374")
-  bundle2-input-part: total payload size 2101
+  bundle2-input-part: total payload size 2139
   bundle2-input-bundle: 4 parts total
   transaction abort!
   rollback completed
@@ -1733,7 +1733,7 @@ Branch acl allow other
   acl: acl.allow not enabled
   acl: acl.deny not enabled
   error: pretxnchangegroup.acl hook failed: acl: user "astro" not allowed on branch "default" (changeset "ef1ea85a6374")
-  bundle2-input-part: total payload size 2101
+  bundle2-input-part: total payload size 2139
   bundle2-input-bundle: 4 parts total
   transaction abort!
   rollback completed
@@ -1805,7 +1805,7 @@ Branch acl allow other
   acl: branch access granted: "e8fc755d4d82" on branch "foobar"
   acl: path access granted: "e8fc755d4d82"
   updating the branch cache
-  bundle2-input-part: total payload size 2101
+  bundle2-input-part: total payload size 2139
   bundle2-input-part: "pushkey" (params: 4 mandatory) supported
   pushing key for "phases:911600dab2ae7a9baff75958b84fe606851ce955"
   bundle2-input-part: "pushkey" (params: 4 mandatory) supported
@@ -1898,7 +1898,7 @@ push foobar into the remote
   acl: branch access granted: "e8fc755d4d82" on branch "foobar"
   acl: path access granted: "e8fc755d4d82"
   updating the branch cache
-  bundle2-input-part: total payload size 2101
+  bundle2-input-part: total payload size 2139
   bundle2-input-part: "pushkey" (params: 4 mandatory) supported
   pushing key for "phases:911600dab2ae7a9baff75958b84fe606851ce955"
   bundle2-input-part: "pushkey" (params: 4 mandatory) supported
@@ -1982,7 +1982,7 @@ Branch acl conflicting deny
   acl: acl.allow not enabled
   acl: acl.deny not enabled
   error: pretxnchangegroup.acl hook failed: acl: user "george" denied on branch "default" (changeset "ef1ea85a6374")
-  bundle2-input-part: total payload size 2101
+  bundle2-input-part: total payload size 2139
   bundle2-input-bundle: 4 parts total
   transaction abort!
   rollback completed
@@ -2059,7 +2059,7 @@ User 'astro' must not be denied
   acl: branch access granted: "e8fc755d4d82" on branch "foobar"
   acl: path access granted: "e8fc755d4d82"
   updating the branch cache
-  bundle2-input-part: total payload size 2101
+  bundle2-input-part: total payload size 2139
   bundle2-input-part: "pushkey" (params: 4 mandatory) supported
   pushing key for "phases:911600dab2ae7a9baff75958b84fe606851ce955"
   bundle2-input-part: "pushkey" (params: 4 mandatory) supported
@@ -2137,7 +2137,7 @@ Non-astro users must be denied
   acl: acl.allow not enabled
   acl: acl.deny not enabled
   error: pretxnchangegroup.acl hook failed: acl: user "george" denied on branch "default" (changeset "ef1ea85a6374")
-  bundle2-input-part: total payload size 2101
+  bundle2-input-part: total payload size 2139
   bundle2-input-bundle: 4 parts total
   transaction abort!
   rollback completed
diff --git a/tests/test-excessive-merge.t b/tests/test-excessive-merge.t
--- a/tests/test-excessive-merge.t
+++ b/tests/test-excessive-merge.t
@@ -69,7 +69,7 @@
        1        60      62  .....       1 96155394af80 5e0375449e74 000000000000 (re)
        2       122      62  .....       2 92cc4c306b19 5e0375449e74 000000000000 (re)
        3       184      69  .....       3 e16a66a37edd 92cc4c306b19 96155394af80 (re)
-       4       253      29  .....       4 2ee31f665a86 96155394af80 92cc4c306b19 (re)
+       4       253      69  .....       4 2ee31f665a86 96155394af80 92cc4c306b19 (re)
 
 revision 1
   $ hg manifest --debug 1
diff --git a/tests/test-ssh-bundle1.t b/tests/test-ssh-bundle1.t
--- a/tests/test-ssh-bundle1.t
+++ b/tests/test-ssh-bundle1.t
@@ -60,8 +60,8 @@ clone remote via stream
 
   $ hg clone -e "python \"$TESTDIR/dummyssh\"" --uncompressed ssh://user@dummy/remote local-stream
   streaming all changes
-  4 files to transfer, 615 bytes of data
-  transferred 615 bytes in * seconds (*) (glob)
+  4 files to transfer, 602 bytes of data
+  transferred 602 bytes in * seconds (*) (glob)
   searching for changes
   no changes found
   updating to branch default
@@ -82,8 +82,8 @@ clone bookmarks via stream
   $ hg -R local-stream book mybook
   $ hg clone -e "python \"$TESTDIR/dummyssh\"" --uncompressed ssh://user@dummy/local-stream stream2
   streaming all changes
-  4 files to transfer, 615 bytes of data
-  transferred 615 bytes in * seconds (*) (glob)
+  4 files to transfer, 602 bytes of data
+  transferred 602 bytes in * seconds (*) (glob)
   searching for changes
   no changes found
   updating to branch default
diff --git a/tests/test-ssh.t b/tests/test-ssh.t
--- a/tests/test-ssh.t
+++ b/tests/test-ssh.t
@@ -54,8 +54,8 @@ clone remote via stream
 
   $ hg clone -e "python \"$TESTDIR/dummyssh\"" --uncompressed ssh://user@dummy/remote local-stream
   streaming all changes
-  4 files to transfer, 615 bytes of data
-  transferred 615 bytes in * seconds (*) (glob)
+  4 files to transfer, 602 bytes of data
+  transferred 602 bytes in * seconds (*) (glob)
   searching for changes
   no changes found
   updating to branch default
@@ -76,8 +76,8 @@ clone bookmarks via stream
   $ hg -R local-stream book mybook
   $ hg clone -e "python \"$TESTDIR/dummyssh\"" --uncompressed ssh://user@dummy/local-stream stream2
   streaming all changes
-  4 files to transfer, 615 bytes of data
-  transferred 615 bytes in * seconds (*) (glob)
+  4 files to transfer, 602 bytes of data
+  transferred 602 bytes in * seconds (*) (glob)
   searching for changes
   no changes found
   updating to branch default