dirstate: fix some problems for recursive case normalization (issue3342)

file in nested directory causes unexpected abort.

problems below should be fixed for recursive normalization route in
dirstate._normalize():

    1. rsplit() may cause unpacking into more than 2 elements.
       it should be called with 'maxsplit' argument to unpack
       into 'd, f'

    2. 'd' is replaced by normalized value prefixed with
       'self._root', but this makes 'folded' as absolute path,
       and it is unexpected one for caller of recursive
       normalization

mercurial/dirstate.py

@@ -406,9 +406,10 b' class dirstate(object):'
                 # recursively normalize leading directory components
                 # against dirstate
                 if '/' in normed:
-                    d, f = normed.rsplit('/')
-                    d = self._root + "/" + self._normalize(d, isknown)
-                    folded = d + "/" + util.fspath(f, d)
+                    d, f = normed.rsplit('/', 1)
+                    d = self._normalize(d, isknown)
+                    r = self._root + "/" + d
+                    folded = d + "/" + util.fspath(f, r)
                 else:
                     folded = util.fspath(normed, self._root)
                 self._foldmap[normed] = folded

tests/test-casefolding.t

@@ -73,6 +73,17 b' no clobbering of untracked files with wr'
 
   $ cd ..
 
+issue 3342: file in nested directory causes unexpected abort
+
+  $ hg init issue3342
+  $ cd issue3342
+
+  $ mkdir -p a/B/c/D
+  $ echo e > a/B/c/D/e
+  $ hg add a/B/c/D/e
+
+  $ cd ..
+
 issue 3340: mq does not handle case changes correctly
 
 in addition to reported case, 'hg qrefresh' is also tested against