[PATCH 4/5] mv: improve overwrite warning

[Jeff King <peff@peff.net>]

When we try to "git mv" over an existing file, the error
message is fairly informative:

  $ git mv one two
  fatal: destination exists, source=one, destination=two

When the user forces the overwrite, we give a warning:

  $ git mv -f one two
  warning: destination exists; will overwrite!

This is less informative, but still sufficient in the simple
rename case, as there is only one rename happening.

But when moving files from one directory to another, it
becomes useless:

  $ mkdir three
  $ touch one two three/one
  $ git add .
  $ git mv one two three
  fatal: destination exists, source=one, destination=three/one
  $ git mv -f one two three
  warning: destination exists; will overwrite!

The first message is helpful, but the second one gives us no
clue about what was overwritten. Instead, let's mirror the
first form more closely, with:

  $ git mv -f one two three
  warning: destination exists (will overwrite), source=one, destination=three/one

Signed-off-by: Jeff King <peff@peff.net>
---
This message looks overly long to me, but I wanted to match the existing
messages. Another option would be just:

  warning: overwriting 'three/one'

 builtin/mv.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/builtin/mv.c b/builtin/mv.c
index ae6c30c..c9ecb03 100644
--- a/builtin/mv.c
+++ b/builtin/mv.c
@@ -177,7 +177,8 @@ int cmd_mv(int argc, const char **argv, const char *prefix)
 				 * check both source and destination
 				 */
 				if (S_ISREG(st.st_mode) || S_ISLNK(st.st_mode)) {
-					warning(_("%s; will overwrite!"), bad);
+					warning(_("%s (will overwrite), source=%s, destination=%s"),
+						bad, src, dst);
 					bad = NULL;
 				} else
 					bad = _("Cannot overwrite");
-- 
1.7.8.13.g74677