stop checking for name existence in pull handler (for now)

This allows pulls, pushes, and other model operations to be performed
with mixed-case names, which the Ollama registry supports.

server/routes.go

@@ -540,11 +540,6 @@ func (s *Server) PullHandler(c *gin.Context) {
 		return
 	}
 
-	if err := checkNameExists(name); err != nil {
-		c.AbortWithStatusJSON(http.StatusBadRequest, gin.H{"error": err.Error()})
-		return
-	}
-
 	ch := make(chan any)
 	go func() {
 		defer close(ch)
@@ -628,7 +623,7 @@ func checkNameExists(name model.Name) error {
 	}
 
 	for n := range names {
-		if strings.EqualFold(n.Filepath(), name.Filepath()) && n != name {
+		if strings.EqualFold(n.Filepath(), name.Filepath()) && n.EqualFold(name) {
 			return errors.New("a model with that name already exists")
 		}
 	}

types/model/name.go

@@ -298,6 +298,13 @@ func (n Name) LogValue() slog.Value {
 	return slog.StringValue(n.String())
 }
 
+func (n Name) EqualFold(o Name) bool {
+	return strings.EqualFold(n.Host, o.Host) &&
+		strings.EqualFold(n.Namespace, o.Namespace) &&
+		strings.EqualFold(n.Model, o.Model) &&
+		strings.EqualFold(n.Tag, o.Tag)
+}
+
 func isValidLen(kind partKind, s string) bool {
 	switch kind {
 	case kindHost: