Revert "Build-in "git-shell""

This reverts commit daa0cc9a92.
It was a stupid idea to do this; when run as a log-in shell,
it is spawned with argv[0] set to "-git-shell", so the usual
name-based dispatch would not work to begin with.

Makefile

@@ -546,7 +546,6 @@ BUILTIN_OBJS += builtin-rev-parse.o
 BUILTIN_OBJS += builtin-revert.o
 BUILTIN_OBJS += builtin-rm.o
 BUILTIN_OBJS += builtin-send-pack.o
-BUILTIN_OBJS += builtin-shell.o
 BUILTIN_OBJS += builtin-shortlog.o
 BUILTIN_OBJS += builtin-show-branch.o
 BUILTIN_OBJS += builtin-show-ref.o
@@ -822,6 +821,7 @@ EXTLIBS += -lz
 ifndef NO_POSIX_ONLY_PROGRAMS
 	PROGRAMS += git-daemon$X
 	PROGRAMS += git-imap-send$X
+	PROGRAMS += git-shell$X
 endif
 ifndef NO_OPENSSL
 	OPENSSL_LIBSSL = -lssl

builtin.h

@@ -88,7 +88,6 @@ extern int cmd_rev_parse(int argc, const char **argv, const char *prefix);
 extern int cmd_revert(int argc, const char **argv, const char *prefix);
 extern int cmd_rm(int argc, const char **argv, const char *prefix);
 extern int cmd_send_pack(int argc, const char **argv, const char *prefix);
-extern int cmd_shell(int argc, const char **argv, const char *prefix);
 extern int cmd_shortlog(int argc, const char **argv, const char *prefix);
 extern int cmd_show(int argc, const char **argv, const char *prefix);
 extern int cmd_show_branch(int argc, const char **argv, const char *prefix);

git.c

@@ -338,7 +338,6 @@ static void handle_internal_command(int argc, const char **argv)
 		{ "revert", cmd_revert, RUN_SETUP | NEED_WORK_TREE },
 		{ "rm", cmd_rm, RUN_SETUP },
 		{ "send-pack", cmd_send_pack, RUN_SETUP },
-		{ "shell", cmd_shell },
 		{ "shortlog", cmd_shortlog, USE_PAGER },
 		{ "show-branch", cmd_show_branch, RUN_SETUP },
 		{ "show", cmd_show, RUN_SETUP | USE_PAGER },

shell.c

@@ -2,7 +2,6 @@
 #include "quote.h"
 #include "exec_cmd.h"
 #include "strbuf.h"
-#include "builtin.h"
 
 static int do_generic_cmd(const char *me, char *arg)
 {
@@ -45,7 +44,7 @@ static struct commands {
 	{ NULL },
 };
 
-int cmd_shell(int argc, const char **argv, const char *prefix)
+int main(int argc, char **argv)
 {
 	char *prog;
 	struct commands *cmd;
@@ -63,7 +62,7 @@ int cmd_shell(int argc, const char **argv, const char *prefix)
 	else if (argc != 3 || strcmp(argv[1], "-c"))
 		die("What do you think I am? A shell?");
 
-	prog = xstrdup(argv[2]);
+	prog = argv[2];
 	if (!strncmp(prog, "git", 3) && isspace(prog[3]))
 		/* Accept "git foo" as if the caller said "git-foo". */
 		prog[3] = '-';