Avoid extra filelogs entries.

Right now, there are some situations in which localrepo.filecommit can
create filelog entries even though they're not needed.  For example:

- permissions for a file have changed;

- qrefresh can create a filelog entry identical to its parent (see the
  added test);

- convert-repo creates extra filelog entries in every merge where the
  first parent has added files (for example, changeset ebebe9577a1a of
  the kernel repo added extra filelog entries to files in the
  arch/blackfin directory, even though the merge should only touch the
  drivers/ata directory).  This makes "hg log file" in a converted repo
  less useful than it could be, since it may mention many merges that
  don't actually touch that specific file.

They all come from the same basic problem:  localrepo.commit (through
filecommit) creates new filelog entries for all files passed to it
(except for some cases during a merge).

Patch and test case provided by Benoit.

This should fix issue351.

tests/test-extra-filelog-entry

@@ -0,0 +1,19 b''
+#!/bin/sh
+#
+# test for issue351
+
+# Environement setup for MQ
+echo "[extensions]" >> $HGRCPATH
+echo "mq=" >> $HGRCPATH
+
+#Repo init
+hg init
+hg qinit
+
+echo b > b
+hg ci -A -m foo
+echo cc > b
+hg qnew -f foo.diff
+echo b > b
+hg qrefresh
+hg debugindex .hg/store/data/b.i

tests/test-extra-filelog-entry.out

@@ -0,0 +1,3 b''
+adding b
+   rev    offset  length   base linkrev nodeid       p1           p2
+     0         0       3      0       0 1e88685f5dde 000000000000 000000000000

mercurial/localrepo.py

@@ -693,9 +693,9 b' class localrepository(repo.repository):'
             elif fpa == fp2:
                 fp2 = nullid
 
-            # is the file unmodified from the parent? report existing entry
-            if fp2 == nullid and not fl.cmp(fp1, t):
-                return fp1
+        # is the file unmodified from the parent? report existing entry
+        if fp2 == nullid and not fl.cmp(fp1, t):
+            return fp1
 
         changelist.append(fn)
         return fl.add(t, meta, transaction, linkrev, fp1, fp2)

tests/test-flags.out

@@ -14,9 +14,9 b' searching for changes'
 adding changesets
 adding manifests
 adding file changes
-added 1 changesets with 1 changes to 1 files (+1 heads)
+added 1 changesets with 0 changes to 0 files (+1 heads)
 (run 'hg heads' to see heads, 'hg merge' to merge)
-changeset:   2:b833d578451e
+changeset:   2:37dccb76c058
 tag:         tip
 parent:      0:4536b1c2ca69
 user:        test
@@ -28,7 +28,7 b' user: test'
 date:        Mon Jan 12 13:46:40 1970 +0000
 summary:     a updated
 
-changeset:   2:b833d578451e
+changeset:   2:37dccb76c058
 tag:         tip
 parent:      0:4536b1c2ca69
 user:        test
@@ -46,17 +46,16 b' date: Mon Jan 12 13:46:40 1970 +0'
 summary:     added a b
 
 resolving manifests
-merging a
-0 files updated, 1 files merged, 0 files removed, 0 files unresolved
+0 files updated, 0 files merged, 0 files removed, 0 files unresolved
 (branch merge, don't forget to commit)
 pulling from ../test2
 searching for changes
 adding changesets
 adding manifests
 adding file changes
-added 1 changesets with 1 changes to 1 files (+1 heads)
+added 1 changesets with 0 changes to 0 files (+1 heads)
 (run 'hg heads' to see heads, 'hg merge' to merge)
-changeset:   2:b833d578451e
+changeset:   2:37dccb76c058
 tag:         tip
 parent:      0:4536b1c2ca69
 user:        test
@@ -68,7 +67,7 b' user: test'
 date:        Mon Jan 12 13:46:40 1970 +0000
 summary:     b updated
 
-changeset:   2:b833d578451e
+changeset:   2:37dccb76c058
 tag:         tip
 parent:      0:4536b1c2ca69
 user:        test
@@ -86,19 +85,15 b' date: Mon Jan 12 13:46:40 1970 +0'
 summary:     added a b
 
 resolving manifests
-getting a
-1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+0 files updated, 0 files merged, 0 files removed, 0 files unresolved
 (branch merge, don't forget to commit)
 -rwxr-x---
 -rwxr-x---
 -rwxr-x---
    rev    offset  length   base linkrev nodeid       p1           p2
      0         0       0      0       0 b80de5d13875 000000000000 000000000000
-     1         0       0      0       2 37c42bd6cc03 b80de5d13875 000000000000
    rev    offset  length   base linkrev nodeid       p1           p2
      0         0       0      0       0 b80de5d13875 000000000000 000000000000
-     1         0       0      0       1 37c42bd6cc03 b80de5d13875 000000000000
    rev    offset  length   base linkrev nodeid       p1           p2
      0         0       0      0       0 b80de5d13875 000000000000 000000000000
      1         0       5      1       1 7fe919cc0336 b80de5d13875 000000000000
-     2         5       0      2       2 37c42bd6cc03 b80de5d13875 000000000000