git-commit: filter out log message lines only when editor was run.

The current behaviour strips out lines starting with a # even when fed
through stdin or -m.  This is particularly bad when importing history from
another SCM (tailor 0.9.23 uses git-commit).  In the best cases all lines
are stripped and the commit fails with a confusing "empty log message"
error, but in many cases the commit is done, with loss of information.

Note that it is quite peculiar to just have "#" handled as a leading
comment char here.  One commonly meet CVS: or CG: or STG: as prefixes, and
using GIT: would be more robust as well as consistent with other commit
tools.  However, that would break any tool relying on the # (if any).
Signed-off-by: NYann Dirson <ydirson@altern.org>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

git-commit.sh

@@ -693,13 +693,18 @@ t)
 	fi
 esac
 
-sed -e '
-    /^diff --git a\/.*/{
-	s///
-	q
-    }
-    /^#/d
-' "$GIT_DIR"/COMMIT_EDITMSG |
+if test -z "$no_edit"
+then
+    sed -e '
+        /^diff --git a\/.*/{
+	    s///
+	    q
+	}
+	/^#/d
+    ' "$GIT_DIR"/COMMIT_EDITMSG
+else
+    cat "$GIT_DIR"/COMMIT_EDITMSG
+fi |
 git-stripspace >"$GIT_DIR"/COMMIT_MSG
 
 if cnt=`grep -v -i '^Signed-off-by' "$GIT_DIR"/COMMIT_MSG |