Move the pick_author code to git-sh-setup

At the moment, only git-commit uses that code, to pick the author name,
email and date from a given commit.

This code will be reused in git rebase --interactive.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: dscho

git-commit.sh

@@ -483,34 +483,8 @@ fi >>"$GIT_DIR"/COMMIT_EDITMSG
 # Author
 if test '' != "$use_commit"
 then
-	pick_author_script='
-	/^author /{
-		s/'\''/'\''\\'\'\''/g
-		h
-		s/^author \([^<]*\) <[^>]*> .*$/\1/
-		s/'\''/'\''\'\'\''/g
-		s/.*/GIT_AUTHOR_NAME='\''&'\''/p
-
-		g
-		s/^author [^<]* <\([^>]*\)> .*$/\1/
-		s/'\''/'\''\'\'\''/g
-		s/.*/GIT_AUTHOR_EMAIL='\''&'\''/p
-
-		g
-		s/^author [^<]* <[^>]*> \(.*\)$/\1/
-		s/'\''/'\''\'\'\''/g
-		s/.*/GIT_AUTHOR_DATE='\''&'\''/p
-
-		q
-	}
-	'
-	encoding=$(git config i18n.commitencoding || echo UTF-8)
-	set_author_env=`git show -s --pretty=raw --encoding="$encoding" "$use_commit" |
-	LANG=C LC_ALL=C sed -ne "$pick_author_script"`
-	eval "$set_author_env"
-	export GIT_AUTHOR_NAME
-	export GIT_AUTHOR_EMAIL
-	export GIT_AUTHOR_DATE
+	eval "$(get_author_ident_from_commit "$use_commit")"
+	export GIT_AUTHOR_NAME GIT_AUTHOR_EMAIL GIT_AUTHOR_DATE
 fi
 if test '' != "$force_author"
 then

git-sh-setup.sh

@@ -53,6 +53,33 @@ require_work_tree () {
 	die "fatal: $0 cannot be used without a working tree."
 }
 
+get_author_ident_from_commit () {
+	pick_author_script='
+	/^author /{
+		s/'\''/'\''\\'\'\''/g
+		h
+		s/^author \([^<]*\) <[^>]*> .*$/\1/
+		s/'\''/'\''\'\'\''/g
+		s/.*/GIT_AUTHOR_NAME='\''&'\''/p
+
+		g
+		s/^author [^<]* <\([^>]*\)> .*$/\1/
+		s/'\''/'\''\'\'\''/g
+		s/.*/GIT_AUTHOR_EMAIL='\''&'\''/p
+
+		g
+		s/^author [^<]* <[^>]*> \(.*\)$/\1/
+		s/'\''/'\''\'\'\''/g
+		s/.*/GIT_AUTHOR_DATE='\''&'\''/p
+
+		q
+	}
+	'
+	encoding=$(git config i18n.commitencoding || echo UTF-8)
+	git show -s --pretty=raw --encoding="$encoding" "$1" |
+	LANG=C LC_ALL=C sed -ne "$pick_author_script"
+}
+
 if [ -z "$LONG_USAGE" ]
 then
 	LONG_USAGE="Usage: $0 $USAGE"