Fix column height with column-span content

Fix #1094.

tests/layout/test_column.py

@@ -80,7 +80,7 @@ def test_column_gap(value, width):
 
 
 @assert_no_logs
-def test_column_span():
+def test_column_span_1():
     page, = render_pages('''
       <style>
         @font-face { src: url(weasyprint.otf); font-family: weasyprint }
@@ -110,6 +110,35 @@ def test_column_span():
     assert column1.height == 16
 
 
+@assert_no_logs
+def test_column_span_2():
+    page, = render_pages('''
+      <style>
+        @font-face { src: url(weasyprint.otf); font-family: weasyprint }
+        body { margin: 0; font-family: weasyprint; line-height: 1 }
+        div { columns: 2; width: 10em; column-gap: 0 }
+        section { column-span: all; margin: 1em 0 }
+      </style>
+
+      <div>
+        <section>test</section>
+        abc def
+        ghi jkl
+        mno pqr
+        stu vwx
+      </div>
+    ''')
+    html, = page.children
+    body, = html.children
+    div, = body.children
+    section1, column1, column2 = div.children
+    assert (section1.content_box_x(), section1.content_box_y()) == (0, 16)
+    assert (column1.position_x, column1.position_y) == (0, 3 * 16)
+    assert (column2.position_x, column2.position_y) == (5 * 16, 3 * 16)
+
+    assert column1.height == column2.height == 16 * 4
+
+
 @assert_no_logs
 def test_columns_multipage():
     page1, page2 = render_pages('''

weasyprint/layout/column.py

@@ -139,6 +139,7 @@ def create_column_box(children):
         current_position_y += collapse_margin(adjoining_margins)
         adjoining_margins = []
         column_box = create_column_box(column_children)
+        column_box.position_y = current_position_y
         new_child, _, _, _, _ = block_box_layout(
             context, column_box, float('inf'), skip_stack, containing_block,
             page_is_empty, [], [], [], discard=False)
@@ -160,7 +161,7 @@ def create_column_box(children):
             for i in range(count):
                 # Render the column
                 new_box, resume_at, next_page, _, _ = block_box_layout(
-                    context, column_box, box.content_box_y() + height,
+                    context, column_box, current_position_y + height,
                     column_skip_stack, containing_block, page_is_empty,
                     [], [], [], discard=False)
                 if new_box is None:
@@ -226,7 +227,7 @@ def create_column_box(children):
                 column_skip_stack = skip_stack
 
         # TODO: check box.style['max']-height
-        max_position_y = min(max_position_y, box.content_box_y() + height)
+        max_position_y = min(max_position_y, current_position_y + height)
 
         # Replace the current box children with columns
         i = 0