diff --git a/ext/session/sessionrebase.test b/ext/session/sessionrebase.test
index 559c9fec3d..4b0a96c67a 100644
--- a/ext/session/sessionrebase.test
+++ b/ext/session/sessionrebase.test
@@ -385,5 +385,60 @@ foreach {tn p} {
   } [list REPLACE $p]
 }
 
+#-------------------------------------------------------------------------
+# Check that apply_v2() does not create a rebase buffer for a patchset.
+# And that it is not possible to rebase a patchset.
+#
+do_execsql_test 4.0 {
+  CREATE TABLE t5(o PRIMARY KEY, p, q);
+  INSERT INTO t5 VALUES(1, 2, 3);
+  INSERT INTO t5 VALUES(4, 5, 6);
+}
+foreach {tn cmd rebasable} {
+  1 patchset 0
+  2 changeset 1
+} {
+  proc xConflict {args} { return "OMIT" }
+  do_test 4.1.$tn {
+    execsql {
+      BEGIN;
+      DELETE FROM t5 WHERE o=4;
+    }
+
+    sqlite3session S db main
+    S attach *
+    execsql {
+      INSERT INTO t5 VALUES(4, 'five', 'six');
+    }
+    set P [S $cmd]
+    S delete
+
+    execsql ROLLBACK;
+
+    set ::rebase [sqlite3changeset_apply_v2 db $P xConflict]
+    expr [llength $::rebase]>0
+  } $rebasable
+}
+
+foreach {tn cmd rebasable} {
+  1 patchset 0
+  2 changeset 1
+} {
+  do_test 4.2.$tn {
+    sqlite3session S db main
+    S attach *
+    execsql {
+      INSERT INTO t5 VALUES(5+$tn, 'five', 'six');
+    }
+    set P [S $cmd]
+    S delete
+
+    sqlite3rebaser_create R
+    R configure $::rebase
+    expr [catch {R rebase $P}]==0
+  } $rebasable
+
+  catch { R delete }
+}
 finish_test
 
diff --git a/ext/session/sqlite3session.c b/ext/session/sqlite3session.c
index 6d38d0ba9d..3abe4697f1 100644
--- a/ext/session/sqlite3session.c
+++ b/ext/session/sqlite3session.c
@@ -5024,6 +5024,9 @@ int sqlite3changeset_concat_strm(
   return rc;
 }
 
+/*
+** Changeset rebaser handle.
+*/
 struct sqlite3_rebaser {
   sqlite3_changegroup grp;        /* Hash table */
 };
@@ -5064,6 +5067,25 @@ static void sessionAppendRecordMerge(
   }
 }
 
+/*
+** This function is called when rebasing a local UPDATE change against one 
+** or more remote UPDATE changes. The aRec/nRec buffer contains the current
+** old.* and new.* records for the change. The rebase buffer (a single
+** record) is in aChange/nChange. The rebased change is appended to buffer
+** pBuf.
+**
+** Rebasing the UPDATE involves: 
+**
+**   * Removing any changes to fields for which the corresponding field
+**     in the rebase buffer is set to "replaced" (type 0xFF). If this
+**     means the UPDATE change updates no fields, nothing is appended
+**     to the output buffer.
+**
+**   * For each field modified by the local change for which the 
+**     corresponding field in the rebase buffer is not "undefined" (0x00)
+**     or "replaced" (0xFF), the old.* value is replaced by the value
+**     in the rebase buffer.
+*/
 static void sessionAppendPartialUpdate(
   SessionBuffer *pBuf,            /* Append record here */
   sqlite3_changeset_iter *pIter,  /* Iterator pointed at local change */
@@ -5117,6 +5139,21 @@ static void sessionAppendPartialUpdate(
   }
 }
 
+/*
+** pIter is configured to iterate through a changeset. This function rebases 
+** that changeset according to the current configuration of the rebaser 
+** object passed as the first argument. If no error occurs and argument xOutput
+** is not NULL, then the changeset is returned to the caller by invoking
+** xOutput zero or more times and SQLITE_OK returned. Or, if xOutput is NULL,
+** then (*ppOut) is set to point to a buffer containing the rebased changeset
+** before this function returns. In this case (*pnOut) is set to the size of
+** the buffer in bytes.  It is the responsibility of the caller to eventually
+** free the (*ppOut) buffer using sqlite3_free(). 
+**
+** If an error occurs, an SQLite error code is returned. If ppOut and
+** pnOut are not NULL, then the two output parameters are set to 0 before
+** returning.
+*/
 static int sessionRebase(
   sqlite3_rebaser *p,             /* Rebaser hash table */
   sqlite3_changeset_iter *pIter,  /* Input data */
@@ -5132,7 +5169,7 @@ static int sessionRebase(
   SessionTable *pTab = 0;
   SessionBuffer sOut = {0,0,0};
 
-  while( SQLITE_ROW==sessionChangesetNext(pIter, &aRec, &nRec, &bNew) ){
+    while( SQLITE_ROW==sessionChangesetNext(pIter, &aRec, &nRec, &bNew) ){
     SessionChange *pChange = 0;
     int bDone = 0;
 
diff --git a/manifest b/manifest
index 46d6d32571..f27d413eb1 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Remove\ssome\sunused\scode\sfrom\sthe\ssessions\smodule.
-D 2018-03-22T11:15:59.453
+C Add\stests\sto\sensure\sthat\spatchsets\sare\shandled\scorrectly\sby\sthe\ssession\srebase\nAPIs.
+D 2018-03-22T14:07:36.942
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F Makefile.in 7016fc56c6b9bfe5daac4f34be8be38d8c0b5fab79ccbfb764d3b23bf1c6fff3
@@ -400,10 +400,10 @@ F ext/session/sessionat.test efe88965e74ff1bc2af9c310b28358c02d420c1fb2705cc7a28
 F ext/session/sessiondiff.test ad13dd65664bae26744e1f18eb3cbd5588349b7e9118851d8f9364248d67bcec
 F ext/session/sessionfault.test da273f2712b6411e85e71465a1733b8501dbf6f7
 F ext/session/sessionfault2.test 883c8919ebcf6c140ba86b480bc14ae642ee9969c009e0b355c8981a5266f9ed
-F ext/session/sessionrebase.test 7cb11b80e6bc13756ac8a51a0601a11f124ee1aa3b1e9eab61ed660b8cab0ef4
+F ext/session/sessionrebase.test cfcbb5649d0fb2568651413d0b1bcf462f2d67a7f31f7a30feb84eaaaada2638
 F ext/session/sessionstat1.test 41cd97c2e48619a41cdf8ae749e1b25f34719de638689221aa43971be693bf4e
 F ext/session/sessionwor.test 2f3744236dc8b170a695b7d8ddc8c743c7e79fdc
-F ext/session/sqlite3session.c 8cea7c63efa1e217d99ffeb3e67199c9538cf7fe5373c1d2ac2b62a691a2dc55
+F ext/session/sqlite3session.c c2e9047c95d769b6e2c3fb28bbdb4972489b08f614bfd95c1a7f86ac0db7ac54
 F ext/session/sqlite3session.h 5f40a0660ff972c0c50f5fd6b33488fdbd2eb0c1244ea95777f8dbd5e529be04
 F ext/session/test_session.c f253742ea01b089326f189b5ae15a5b55c1c9e97452e4a195ee759ba51b404d5
 F ext/userauth/sqlite3userauth.h 7f3ea8c4686db8e40b0a0e7a8e0b00fac13aa7a3
@@ -1716,7 +1716,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P d00b71ecf857bc6d903442d91418d5a313c584dcdd8e9c8ff3b5d940dd45bcc5
-R 1a609de137c9dc0274aa7feaed1a7236
+P a09518ab63a1ef1b7f56b9f9b16269fd83920469d4c4e179b1f68b35df4e0c4b
+R 540efa4ba550adb2ed0df3b20fe42653
 U dan
-Z 10aaa03ec1ff02e2361d604078258cf8
+Z d881b19a01a687698d13e50ca6bf2cbd
diff --git a/manifest.uuid b/manifest.uuid
index 95d2cb6f81..20f528be06 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-a09518ab63a1ef1b7f56b9f9b16269fd83920469d4c4e179b1f68b35df4e0c4b
\ No newline at end of file
+0e45baaec01947f6cbf47d5d5922a4cabe7d27181c04c0a08259c952fd023947
\ No newline at end of file