Update
This problem has been fixed by a paclet update -- specifically version 10.2.1 of the GeneralUtilities paclet:
PacletFind["GeneralUtilities"] // PacletInformation //
GeneralUtilities`ToAssociations // Dataset

In chat, Arnoud Buzing stated that this patch will normally be loaded automatically during the weekly paclet update. He also offered the following steps to perform the update manually:
Evaluate these expressions:
PacletSiteUpdate /@ PacletSites[];
PacletInstall /@ PacletFindRemote["WolframAutoUpdate"];
PacletInstall /@ PacletFindRemote["GeneralUtilities"];
Quit and restart the kernel.
Original Response
As we await a fix from WRI, we can remove the errant Print
as follows:
Needs["GeneralUtilities`"]
DownValues[GeneralUtilities`AssociationTranspose] =
DeleteCases[
DownValues[GeneralUtilities`AssociationTranspose]
, HoldPattern @
Print[
GeneralUtilities`General`PackagePrivate`ikeys
, GeneralUtilities`General`PackagePrivate`keys
, GeneralUtilities`General`PackagePrivate`vals
]
, Infinity
]
Naturally, this will void your warranty...
Block[{Print}, ds[Transpose]]
? (Don't have V10.2 yet.) $\endgroup$