Using ^{} as the peel suffix has caused problems when projects used
tags like v2.1 and then v2.1.1, v2.2.2, etc. The peeled value for
v2.1 was stored very far away in the tree relative to v2.1 itself as
^ sorts in the ASCII/UTF-8 encoding after all other common tag
characters like digits and dots.
Use " ^" instead as space is not valid in a reference name, sorts
before all other valid reference characters (thus forcing next entry
locality) and this looks like a peeled marker for the prior tag.
Change-Id: I26d2247a0428dfe26a9c319c02159502b3a67455
398d8e877f