localrepo: don't add deleted files to list of modified/added files (issue2761)

If a file is deleted (rm, not 'hg rm') from the working dir
an attempt to run 'hg diff -r X', with the file being present in X will
cause an abort.

We didn't check if the file has been deleted from the working dir
and later on tried to open it to compare with the one from X, causing the abort.

This fix adds that check. Consequently, no output will be returned.

tests/test-diff-issue2761.t

@@ -0,0 +1,23 b''
+Test issue2761
+
+  $ hg init
+
+  $ touch to-be-deleted
+  $ hg add
+  adding to-be-deleted
+  $ hg ci -m first
+  $ echo a > to-be-deleted
+  $ hg ci -m second
+  $ rm to-be-deleted
+  $ hg diff -r 0
+
+Same issue, different code path
+
+  $ hg up -C
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ touch doesnt-exist-in-1
+  $ hg add
+  adding doesnt-exist-in-1
+  $ hg ci -m third
+  $ rm doesnt-exist-in-1
+  $ hg diff -r 1

mercurial/localrepo.py

@@ -1225,14 +1225,15 b' class localrepository(repo.repository):'
             modified, added, clean = [], [], []
             for fn in mf2:
                 if fn in mf1:
-                    if (mf1.flags(fn) != mf2.flags(fn) or
+                    if (fn not in deleted and
+                        (mf1.flags(fn) != mf2.flags(fn) or
                         (mf1[fn] != mf2[fn] and
-                         (mf2[fn] or ctx1[fn].cmp(ctx2[fn])))):
+                          (mf2[fn] or ctx1[fn].cmp(ctx2[fn]))))):
                         modified.append(fn)
                     elif listclean:
                         clean.append(fn)
                     del mf1[fn]
-                else:
+                elif fn not in deleted:
                     added.append(fn)
             removed = mf1.keys()
 

tests/test-mq-qdiff.t

@@ -163,4 +163,13 b' qdiff preserve existing git flag:'
   $ hg qdiff --stat
    lines |  7 +++++--
    1 files changed, 5 insertions(+), 2 deletions(-)
+  $ hg qrefresh
 
+qdiff when file deleted (but not removed) in working dir:
+
+  $ hg qnew deleted-file
+  $ echo a > newfile
+  $ hg add newfile
+  $ hg qrefresh
+  $ rm newfile
+  $ hg qdiff