largefiles: don't interfere with logging normal files

The previous code was adding standin files to the matcher's file list when
neither the standin file nor the original existed in the context.  Somehow, this
was confusing the logging code into behaving differently from when the extension
wasn't loaded.

It seems that this was an attempt to support naming a directory that only
contains largefiles, as a test fails if the else clause is dropped entirely.
Therefore, only append the "standin" if it is a directory.  This was found by
running the test suite with --config extensions.largefiles=.

The first added test used to log an additional cset that wasn't logged normally.
The only relation it had to file 'a' is that 'a' was the source of a move, but
it isn't clear why having '.hglf/a' in the list causes this change:

    @@ -47,6 +47,11 @@

     Make sure largefiles doesn't interfere with logging a regular file
       $ hg log a --config extensions.largefiles=
    +  changeset:   3:2ca5ba701980
    +  user:        test
    +  date:        Thu Jan 01 00:00:04 1970 +0000
    +  summary:     d
    +
       changeset:   0:9161b9aeaf16
       user:        test
       date:        Thu Jan 01 00:00:01 1970 +0000

The second added test used to complain about a file not being in the parent
revision:

    @@ -1638,10 +1643,8 @@

     Ensure that largefiles doesn't intefere with following a normal file
       $ hg  --config extensions.largefiles= log -f d -T '{desc}' -G
    -  @  c
    -  |
    -  o  a
    -
    +  abort: cannot follow file not in parent revision: ".hglf/d"
    +  [255]
       $ hg log -f d/a -T '{desc}' -G
       @  c
       |

Note that there is still something fishy with the largefiles code, because when
using a glob pattern like this:

    $ hg log 'glob:sub/*'

the pattern list would contain '.hglf/glob:sub/*'.  None of the tests show this
(this test lives in test-largefiles.t at 1349), it was just something that I
noticed when the code was loaded up with print statements.

hgext/largefiles/overrides.py

@@ -316,9 +316,14 b' def overridelog(orig, ui, repo, *pats, *'
 
         for i in range(0, len(m._files)):
             standin = lfutil.standin(m._files[i])
+            # If the "standin" is a directory, append instead of replace to
+            # support naming a directory on the command line with only
+            # largefiles.  The original directory is kept to support normal
+            # files.
             if standin in repo[ctx.node()]:
                 m._files[i] = standin
-            elif m._files[i] not in repo[ctx.node()]:
+            elif m._files[i] not in repo[ctx.node()] \
+                    and repo.wvfs.isdir(standin):
                 m._files.append(standin)
             pats.add(standin)
 

tests/test-log.t

@@ -45,6 +45,13 b' changeset graph'
   $ hg mv dir/b e
   $ hg ci -me -d '5 0'
 
+Make sure largefiles doesn't interfere with logging a regular file
+  $ hg log a --config extensions.largefiles=
+  changeset:   0:9161b9aeaf16
+  user:        test
+  date:        Thu Jan 01 00:00:01 1970 +0000
+  summary:     a
+  
   $ hg log a
   changeset:   0:9161b9aeaf16
   user:        test
@@ -1629,6 +1636,12 b' hg log -f dir across branches'
   |
   o  a
   
+Ensure that largefiles doesn't intefere with following a normal file
+  $ hg  --config extensions.largefiles= log -f d -T '{desc}' -G
+  @  c
+  |
+  o  a
+  
   $ hg log -f d/a -T '{desc}' -G
   @  c
   |