[PATCH 2/2 v2] run-command (Windows): Run dashless "git <cmd>" (solves part of problem with system_path)

We prefer running the dashless form, so we should use it in MinGW's
start_command(), too.

This solves a fundamental problem we have with the computation of system
directories based on relative paths in combination with the new
gitexecpath 'libexec/git-core'.  The problem is that the program 'git'
is hardlinked to directories with different depth.  It is either used as
'bin/git' (1 directory) or as 'libexec/git-core/git-*' (2 directories).
Thus, using the same relative path in system_path() yields different
results when starting from the two locations.  I recognized the problem
because /etc/gitconfig is no longer read.

This commit fixes the problem by always calling 'bin/git' for builtin
commands.  The computation in system_path() thus always starts from
'bin' and yields predictable results.  This is however only part of a
full solution to the problem outlined above.  Remaining problems are:

 - Other code paths might run the dashed forms directly.

 - We have non-builtins that are implemented in C, e.g. fast-import.c.
   These non-builtins will still compute wrong paths.

Signed-off-by: Steffen Prohaska <redacted>
Acked-by: Johannes Sixt <redacted>
---
 run-command.c |   11 ++++-------
 1 files changed, 4 insertions(+), 7 deletions(-)

My previous mail was in the wrong thread.  Apologies.  This one
will be correctly threaded.

    Steffen

diff --git a/run-command.c b/run-command.c
index 6e29fdf..a3b28a6 100644
--- a/run-command.c
+++ b/run-command.c

@@ -119,9 +119,8 @@ int start_command(struct child_process *cmd)
 	}
 #else
 	int s0 = -1, s1 = -1, s2 = -1;	/* backups of stdin, stdout, stderr */
-	const char *sargv0 = cmd->argv[0];
+	const char **sargv = cmd->argv;
 	char **env = environ;
-	struct strbuf git_cmd;
 
 	if (cmd->no_stdin) {
 		s0 = dup(0);

@@ -165,9 +164,7 @@ int start_command(struct child_process *cmd)
 	}
 
 	if (cmd->git_cmd) {
-		strbuf_init(&git_cmd, 0);
-		strbuf_addf(&git_cmd, "git-%s", cmd->argv[0]);
-		cmd->argv[0] = git_cmd.buf;
+		cmd->argv = prepare_git_cmd(cmd->argv);
 	}
 
 	cmd->pid = mingw_spawnvpe(cmd->argv[0], cmd->argv, env);

@@ -175,9 +172,9 @@ int start_command(struct child_process *cmd)
 	if (cmd->env)
 		free_environ(env);
 	if (cmd->git_cmd)
-		strbuf_release(&git_cmd);
+		free(cmd->argv);
 
-	cmd->argv[0] = sargv0;
+	cmd->argv = sargv;
 	if (s0 >= 0)
 		dup2(s0, 0), close(s0);
 	if (s1 >= 0)

-- 
1.6.0.rc0.79.gb0320