Store empty (default) branch in branch cache, too.
Operations on this branch don't work otherwise.
Reading branches.cache had to be adjusted to allow an empty label.
Adjusted reading of the cache tip for symmetry, no functional change here.
#!/usr/bin/env python
import sys
from mercurial import bdiff, mpatch
def test1(a, b):
d = bdiff.bdiff(a, b)
c = a
if d:
c = mpatch.patches(a, [d])
if c != b:
print "***", `a`, `b`
print "bad:"
print `c`[:200]
print `d`
def test(a, b):
print "***", `a`, `b`
test1(a, b)
test1(b, a)
test("a\nc\n\n\n\n", "a\nb\n\n\n")
test("a\nb\nc\n", "a\nc\n")
test("", "")
test("a\nb\nc", "a\nb\nc")
test("a\nb\nc\nd\n", "a\nd\n")
test("a\nb\nc\nd\n", "a\nc\ne\n")
test("a\nb\nc\n", "a\nc\n")
test("a\n", "c\na\nb\n")
test("a\n", "")
test("a\n", "b\nc\n")
test("a\n", "c\na\n")
test("", "adjfkjdjksdhfksj")
test("", "ab")
test("", "abc")
test("a", "a")
test("ab", "ab")
test("abc", "abc")
test("a\n", "a\n")
test("a\nb", "a\nb")
print "done"