localrepo: don't allow lookup of working directory revision

It seems that repo.lookup(), which is what supports the "lookup" wire
protocol command, should not allow the working copy revision
input.

This fixes both the pull test and the convert test I just added.

Differential Revision: https://phab.mercurial-scm.org/D6215

mercurial/localrepo.py

@@ -1564,7 +1564,10 b' class localrepository(object):'
                 pass
 
     def lookup(self, key):
-        return scmutil.revsymbol(self, key).node()
+        node = scmutil.revsymbol(self, key).node()
+        if node is None:
+            raise error.RepoLookupError(_("unknown revision '%s'") % key)
+        return node
 
     def lookupbranch(self, key):
         if self.branchmap().hasbranch(key):

tests/test-convert-hg-source.t

@@ -218,11 +218,10 b' manifest -r tip'
   $ hg ci -Aqm 'the working copy is called ffffffffffff'
 
   $ cd ..
-BROKEN: crashes when the "ffffffffffff" is encountered
   $ hg convert commit-references new-commit-references -q \
-  >     --config convert.hg.sourcename=yes 2>&1 | grep TypeError
-  TypeError: b2a_hex() argument 1 must be string or buffer, not None
+  >     --config convert.hg.sourcename=yes
   $ cd new-commit-references
   $ hg log -T '{node|short} {desc}\n'
+  fe295c9e6bc6 the working copy is called ffffffffffff
   642508659503 the previous commit was c2491f685436
   c2491f685436 initial

tests/test-pull.t

@@ -76,10 +76,9 b' not are encoded like a node:'
   [255]
 
 Test pull of working copy revision
-BROKEN: should give a better error message
   $ hg pull -r 'ffffffffffff'
   pulling from http://foo@localhost:$HGPORT/
-  abort: b2a_hex() argument 1 must be string or buffer, not None!
+  abort: unknown revision 'ffffffffffff'!
   [255]
 
 Issue622: hg init && hg pull -u URL doesn't checkout default branch