Omit an branch made unreachable by the improved error message from dropping

the last column of a table.

FossilOrigin-Name: c5719fc5aa04c50bb01533f1cedb73dc80c4bf5315ff6a7206c8a10504afca8b

manifest

@@ -1,5 +1,5 @@
-C The\sCOLUMN\skeyword\sin\sALTER\sTABLE\sDROP\sCOLUMN\sis\soptional.
-D 2021-02-19T09:36:50.687
+C Omit\san\sbranch\smade\sunreachable\sby\sthe\simproved\serror\smessage\sfrom\sdropping\nthe\slast\scolumn\sof\sa\stable.
+D 2021-02-19T09:46:52.358
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -475,7 +475,7 @@ F spec.template 86a4a43b99ebb3e75e6b9a735d5fd293a24e90ca
 F sqlite.pc.in 42b7bf0d02e08b9e77734a47798d1a55a9e0716b
 F sqlite3.1 fc7ad8990fc8409983309bb80de8c811a7506786
 F sqlite3.pc.in 48fed132e7cb71ab676105d2a4dc77127d8c1f3a
-F src/alter.c ae5ff195830c9fb15869067340ab3e619fb41332907c75f0fd0c8756e4a3826d
+F src/alter.c 4dc2c97b49c555e624783caaa50ae27c23be9933c64e26e4a033366ab60c30f2
 F src/analyze.c 01c6c6765cb4d40b473b71d85535093730770bb186f2f473abac25f07fcdee5c
 F src/attach.c e80162a47411f296bea550ed8fafd730481f4aa71e89ece23ba9c957eed15d4a
 F src/auth.c 08954fdc4cc2da5264ba5b75cfd90b67a6fc7d1710a02ccf917c38eadec77853
@@ -1902,7 +1902,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 5e1f362bc3e53c60f9e6f771346d10c6e6a6cb3ff1eec5608101f9c5d6d2a5a4
-R d4c9013c313cab1e0a7971c4b14f44ef
+P a22f87fb6c43dd6217691c8dd1cdcd7880068024fb779ca8a5def068d72c3e6b
+R 8fe145aa3933b8b7851e138e048197cd
 U drh
-Z f136680b9ca40f702c72664ef013c51c
+Z 50b646c8c422b4be2f6044aaaf70a38b

manifest.uuid

@@ -1 +1 @@
-a22f87fb6c43dd6217691c8dd1cdcd7880068024fb779ca8a5def068d72c3e6b
+c5719fc5aa04c50bb01533f1cedb73dc80c4bf5315ff6a7206c8a10504afca8b

src/alter.c

@@ -1816,7 +1816,7 @@ static void dropColumnFunc(
     zEnd = (const char*)pEnd->t.z;
   }else{
     zEnd = (const char*)&zSql[iAddColOffset];
-    while( pCol->t.z[0]!=',' && pCol->t.z[1]!='(' ) pCol->t.z--;
+    while( ALWAYS(pCol->t.z[0]!=0) && pCol->t.z[0]!=',' ) pCol->t.z--;
   }
 
   zNew = sqlite3MPrintf(db, "%.*s%s", pCol->t.z-zSql, zSql, zEnd);