Strings of the pattern \$\d seem to be getting substituted out. This is resulting in simple dollar amounts being mangled. I imagine this could be due to some step where those values are being run through a step that results shell command substitution of values like $1, $2, etc.
EXAMPLE (run on git-diff@2.0.6):
console.log( gitDiff("How about $2?\n","How 'bout $2?\n") )
EXPECTED RESULT:
@@ -1 +1 @@
-How about $2?
+How 'bout $2?
ACTUAL RESULT:
@@ -1 +1 @@
-How about ?
+How 'bout ?