The BtCursor.info fields are only valid if info.nSize!=0.

FossilOrigin-Name: 54c537eead5b08104cfaf0d5b1e2706e53d6f74be2ca02e06229024fd889fc94

manifest

@@ -1,5 +1,5 @@
-C Add\smore\scorruption\schecking\sto\sthe\scell\soverwrite\slogic.
-D 2018-05-03T13:56:23.121
+C The\sBtCursor.info\sfields\sare\sonly\svalid\sif\sinfo.nSize!=0.
+D 2018-05-03T14:07:18.080
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F Makefile.in 5ce9343cba9c189046f1afe6d2bcc1f68079439febc05267b98aec6ecc752439
@@ -434,7 +434,7 @@ F src/auth.c 6277d63837357549fe14e723490d6dc1a38768d71c795c5eb5c0f8a99f918f73
 F src/backup.c faf17e60b43233c214aae6a8179d24503a61e83b
 F src/bitvec.c 17ea48eff8ba979f1f5b04cc484c7bb2be632f33
 F src/btmutex.c 8acc2f464ee76324bf13310df5692a262b801808984c1b79defb2503bbafadb6
-F src/btree.c ffaf0f6524095774527460de0ffe362fb463fed2ceecf79acbd93ad517a6f26d
+F src/btree.c edb3c69a73cf7c0286dbe040b0ea7069e606e54fd1ee60bbe1e63e56fba0e2b7
 F src/btree.h 0866c0a08255142ea0e754aabd211c843cab32045c978a592a43152405ed0c84
 F src/btreeInt.h 620ab4c7235f43572cf3ac2ac8723cbdf68073be4d29da24897c7b77dda5fd96
 F src/build.c 0c2be5839f22aa2938f217c6c6c2120d9fc96872a546a37541a8271541cb355e
@@ -1727,7 +1727,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 0cb6cd2a6a596afaa1cca6c5f5abc2ea75d04f254c7debaf36ecd6a90b66aed6
-R 8c38a5f8c55025ab9be63aa068eb2853
+P 58d14afe1e1288d114ea213458b3121e0a95670887861928858b7f143c76f789
+R b073d403d1ba3bd03f4d3e8e8927a6d3
 U drh
-Z 78d645c2f5a7df7e355a3c554b462bfa
+Z e6a7ba3bea7a5cce16673df821a14231

manifest.uuid

@@ -1 +1 @@
-58d14afe1e1288d114ea213458b3121e0a95670887861928858b7f143c76f789
+54c537eead5b08104cfaf0d5b1e2706e53d6f74be2ca02e06229024fd889fc94

src/btree.c

@@ -8335,7 +8335,7 @@ int sqlite3BtreeInsert(
     if( (pCur->curFlags&BTCF_ValidNKey)!=0 && pX->nKey==pCur->info.nKey ){
       /* The current is currently pointing to the entry that is to be
       ** overwritten */
-      if( pCur->info.nPayload==pX->nData+pX->nZero ){
+      if( pCur->info.nSize!=0 && pCur->info.nPayload==pX->nData+pX->nZero ){
         return btreeOverwriteCell(pCur, pX);
       }
       loc = 0;