Re: Post your SegWit questions here - open discussion - big week for Bitcoin!
Sure, because distinguishing between σ = (r,s) and σ'= (r,N − s) is just too hard for bitcoin, eh? 
Ripple uses (r,s) < (r,N − s)? (r,s):(r,N − s)
Ripple uses (r,s) < (r,N − s)? (r,s):(r,N − s)
This isn't the only source of malleability. The abandoned BIP62 lists ways in which a Bitcoin transaction is malleable:
- Non-DER encoded ECDSA signatures
- Non-push operations in scriptSig
- Push operations in scriptSig of non-standard size type
- Zero-padded number pushes
- Inherent ECDSA signature malleability
- Superfluous scriptSig operations
- Inputs ignored by scripts
- Sighash flags based masking