magit-bisect-run: Don't start bisect asynchronously

As of 56354898 (Run "git bisect" asynchronously, 2019-04-20),
magit-git-bisect runs `git bisect' calls asynchronously.  While
beneficial in most spots, this switch creates a race if
magit-bisect-run is called when a bisect hasn't been started.

In that case, magit-bisect-run calls magit-bisect-start (which calls
the asynchronous magit-git-bisect underneath) and then immediately
follows with a `git bisect run' call via magit-git-bisect.  This
second call depends on the first asynchronous call completing, so it
leads to a "Not bisecting" user error.  That's quickly buried when the
magit-bisect-start call finishes, and the end result looks like the
user just called magit-bisect-start.

Before 56354898, magit-git-bisect used the now removed
magit-run-git-with-logfile.  Inline that code for magit-bisect-run's
start call.

1 files changed, 8 insertions, 1 deletions

diff --git a/lisp/magit-bisect.el b/lisp/magit-bisect.el
index 66aca68..fe43029 100644
--- a/lisp/magit-bisect.el
+++ b/lisp/magit-bisect.el
@@ -196,7 +196,14 @@ bisect run'."
                                 (magit-bisect-start-read-args))))
                  (cons (read-shell-command "Bisect shell command: ") args)))
   (when (and bad good)
-    (magit-bisect-start bad good args))
+    ;; Avoid `magit-git-bisect' because it's asynchronous, but the
+    ;; next `git bisect run' call requires the bisect to be started.
+    (magit-with-toplevel
+      (apply #'magit-process-file magit-git-executable
+             nil (list :file (magit-git-dir "BISECT_CMD_OUTPUT")) nil
+             (magit-process-git-arguments
+              (list "bisect" "start" bad good args)))
+      (magit-refresh)))
   (magit-git-bisect "run" (list shell-file-name shell-command-switch cmdline)))
 
 (defun magit-git-bisect (subcommand &optional args no-assert)