fix(git): stop the blame statuscolumn leaking into new windows

test/git/blame_test.lua

@@ -450,6 +450,32 @@ t.test("overlay re-budgets when a gutter option changes", function()
     end, "the blame to re-budget for the widened signcolumn")
 end)
 
+t.test("the overlay statuscolumn does not leak into other windows", function()
+    local _, buf = setup("a\nb\nc\n")
+    vim.api.nvim_set_current_buf(buf)
+    blame.toggle_overlay(buf)
+    t.wait_for(function()
+        local s = blame.state(buf)
+        return s ~= nil and s.blame_width ~= nil
+    end, "the overlay to render")
+    t.falsy(
+        vim.go.statuscolumn:find("git.blame", 1, true),
+        "the overlay leaves the global statuscolumn untouched"
+    )
+
+    vim.cmd("new")
+    local plain = vim.api.nvim_get_current_win()
+    t.defer(function()
+        if vim.api.nvim_win_is_valid(plain) then
+            vim.api.nvim_win_close(plain, true)
+        end
+    end)
+    t.falsy(
+        vim.wo[plain].statuscolumn:find("git.blame", 1, true),
+        "a new window does not inherit the blame gutter"
+    )
+end)
+
 t.test("overlay gutter shows sha, author and an absolute date", function()
     local _, buf = setup("a\nb\nc\n")
     vim.api.nvim_set_current_buf(buf)