Could it perhaps be something else in the request process causing this? Are you trying this with a browser or cURL? Please try this version and report the results:
when HTTP_REQUEST {
log local0. "path = [HTTP::path]"
log local0. "uri = [HTTP::uri]"
if { [HTTP::path] starts_with "/GoogleAltLogin-2.0.7" } {
log local0. "google"
pool googleAltLogin
elseif { [HTTP::path] starts_with "/banner-mobileserver/" } {
log local0. "slash"
pool local-pool
} elseif { [HTTP::path] starts_with "/banner-mobileserver" } {
log local0. "no slash"
pool local-pool
} else {
log local0. "default"
pool local-pool-single
}
}