[RFC/PATCH] Reduce cost of deletion in levenstein distance (4 -> 3)

[Matthieu Moy <Matthieu.Moy@imag.fr>]

Before this patch, a character deletion has the same cost as 2 swaps, or
4 additions, so Git prefers suggesting a completely scrambled command
name to removing a character. For example, "git tags" suggests "stage",
but not "tag".

By setting the deletion cost to 3, we keep it higher than swaps or
additions, but prefer 1 deletion to 2 swaps. "git tags" now suggests
"tag" in addition to staged.

Signed-off-by: Matthieu Moy <Matthieu.Moy@imag.fr>
---
The funny thing is: A while ago, I reported that the typo "git tags"
was not suggesting "git tag" as alternative "did you mean this?". A
patch was posted and merged:

  http://thread.gmane.org/gmane.comp.version-control.git/101278

According to the discussion, I it worked for me. But I can't reproduce
this "works for me" even going back to the version right after the fix
above.

 help.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/help.c b/help.c
index 14eefc9..fdaa90d 100644
--- a/help.c
+++ b/help.c
@@ -334,7 +334,7 @@ const char *help_unknown_cmd(const char *cmd)
 		}
 
 		main_cmds.names[i]->len =
-			levenshtein(cmd, candidate, 0, 2, 1, 4) + 1;
+			levenshtein(cmd, candidate, 0, 2, 1, 3) + 1;
 	}
 
 	qsort(main_cmds.names, main_cmds.cnt,
-- 
1.7.10.363.g9094b