Refactor ('unvendor') parse_auth_header

sentry/utils/auth.py

@@ -1,8 +1,3 @@
-def _make_key_value(val):
-    # strip, and then split on '='
-    return val.strip().split("=", 1)
-
-
 def parse_auth_header(header):
     # KvS: isn't this always either bytes or strings? I'd like to learn more (first quickly, and then formalizing for
     # actual uses)
@@ -14,8 +9,9 @@ def parse_auth_header(header):
         print("not bytes, already a string")
 
     try:
-        # the the RHS of the header (question: what's left of the space), split it on "," and put the x=y pairs into a
-        # dict as key-values
-        return dict(map(_make_key_value, header.split(" ", 1)[1].split(",")))
+        _, rhs = header.split(" ", 1)
+        return {
+            k: v for (k, v) in [part.strip().split('=', 1) for part in rhs.split(",")]
+        }
     except Exception:
         return {}