Merge branch 'sg/bisect'

* sg/bisect:
  bisect: check for mandatory argument of 'bisect replay'
  bisect: improve error msg of 'bisect reset' when original HEAD is deleted
  bisect: improve error message of 'bisect log' while not bisecting

Author: gitster

git-bisect.sh

@@ -316,7 +316,12 @@ bisect_reset() {
 	*)
 	    usage ;;
 	esac
-	git checkout "$branch" -- && bisect_clean_state
+	if git checkout "$branch" -- ; then
+		bisect_clean_state
+	else
+		die "Could not check out original HEAD '$branch'." \
+				"Try 'git bisect reset <commit>'."
+	fi
 }
 
 bisect_clean_state() {
@@ -338,6 +343,7 @@ bisect_clean_state() {
 }
 
 bisect_replay () {
+	test "$#" -eq 1 || die "No logfile given"
 	test -r "$1" || die "cannot read $1 for replaying"
 	bisect_reset
 	while read git bisect command rev
@@ -412,6 +418,10 @@ bisect_run () {
     done
 }
 
+bisect_log () {
+	test -s "$GIT_DIR/BISECT_LOG" || die "We are not bisecting."
+	cat "$GIT_DIR/BISECT_LOG"
+}
 
 case "$#" in
 0)
@@ -438,7 +448,7 @@ case "$#" in
     replay)
 	bisect_replay "$@" ;;
     log)
-	cat "$GIT_DIR/BISECT_LOG" ;;
+	bisect_log ;;
     run)
         bisect_run "$@" ;;
     *)