--prune is now default for 'pack-refs'

There is no reason not to, really.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

Documentation/git-pack-refs.txt

@@ -7,7 +7,7 @@ git-pack-refs - Pack heads and tags for efficient repository access
 
 SYNOPSIS
 --------
-'git-pack-refs' [--all] [--prune]
+'git-pack-refs' [--all] [--no-prune]
 
 DESCRIPTION
 -----------
@@ -40,10 +40,11 @@ developed and packing their tips does not help performance.
 This option causes branch tips to be packed as well.  Useful for
 a repository with many branches of historical interests.
 
-\--prune::
+\--no-prune::
+
+The command usually removes loose refs under `$GIT_DIR/refs`
+hierarchy after packing them.  This option tells it not to.
 
-After packing the refs, remove loose refs under `$GIT_DIR/refs`
-hierarchy.  This should probably become default.
 
 Author
 ------

builtin-pack-refs.c

@@ -4,7 +4,7 @@
 #include "tag.h"
 
 static const char builtin_pack_refs_usage[] =
-"git-pack-refs [--all] [--prune]";
+"git-pack-refs [--all] [--prune | --no-prune]";
 
 struct ref_to_prune {
 	struct ref_to_prune *next;
@@ -90,10 +90,15 @@ int cmd_pack_refs(int argc, const char **argv, const char *prefix)
 
 	memset(&cbdata, 0, sizeof(cbdata));
 
+	cbdata.prune = 1;
 	for (i = 1; i < argc; i++) {
 		const char *arg = argv[i];
 		if (!strcmp(arg, "--prune")) {
-			cbdata.prune = 1;
+			cbdata.prune = 1; /* now the default */
+			continue;
+		}
+		if (!strcmp(arg, "--no-prune")) {
+			cbdata.prune = 0;
 			continue;
 		}
 		if (!strcmp(arg, "--all")) {

t/t3210-pack-refs.sh

@@ -34,7 +34,7 @@ test_expect_success \
     'see if a branch still exists when packed' \
     'git-branch b &&
      git-pack-refs --all &&
-     rm .git/refs/heads/b &&
+     rm -f .git/refs/heads/b &&
      echo "$SHA1 refs/heads/b" >expect &&
      git-show-ref b >result &&
      diff expect result'