Fix Blocker issue 8487

Custom CRS are saved if cannot find an existing one with same parameters
(except datum which may be optionnal, as GDAL seems to have drop it)

src/core/qgscoordinatereferencesystem.cpp

@@ -593,6 +593,7 @@ bool QgsCoordinateReferenceSystem::createFromProj4( const QString theProj4String
     }
   }
 
+  QStringList myParam;
   if ( myRecord.empty() )
   {
     // match all parameters individually:
@@ -618,6 +619,7 @@ bool QgsCoordinateReferenceSystem::createFromProj4( const QString theProj4String
       {
         sql += delim + arg;
         delim = " AND ";
+        myParam.append(param);
       }
     }
 
@@ -637,9 +639,26 @@ bool QgsCoordinateReferenceSystem::createFromProj4( const QString theProj4String
   {
     mySrsId = myRecord["srs_id"].toLong();
     QgsDebugMsg( "proj4string param match search for srsid returned srsid: " + QString::number( mySrsId ) );
-    if ( mySrsId > 0 )
+    // Bugfix 8487 : test param lists are equal, except for +datum
+    myParam.sort();
+    QStringList foundParam;
+    foreach ( QString paramfound, myRecord["parameters"].split( QRegExp( "\\s+(?=\\+)" ), QString::SkipEmptyParts ) )
     {
-      createFromSrsId( mySrsId );
+      if ( !paramfound.startsWith( "+datum=" ) )
+        foundParam.append(paramfound);
+    }
+    foundParam.sort();
+    if ( myParam == foundParam)
+    {
+        if ( mySrsId > 0 )
+      {
+        createFromSrsId( mySrsId );
+      }
+    }
+    else
+    {
+      // Params differ
+      mIsValidFlag = false;
     }
   }
   else