fix(davs2): use %nil

anda/lib/davs2/davs2.spec

@@ -1,15 +1,15 @@
-%global commit0 
+%global commit0 b41cf117452e2d73d827f02d3e30aa20f1c721ac
 %global date 20220903
 %global shortcommit %(c=%{commit0}; echo ${c:0:7})
 
 Name:       davs2
 Version:    1.7
-Release:    1%?dist
+Release:    1%{?shortcommit:.%{date}git%{shortcommit}}%{?dist}
 Summary:    An open-source decoder of AVS2-P2/IEEE1857.4 video coding standard
 URL:        https://github.com/pkuvcl/%{name}
 License:    GPLv2
 
-%if "%len %{commit0}" != 0
+%if %{commit0} != %nil
 Source0:    https://github.com/pkuvcl/%{name}/archive/%{commit0}/%{name}-%{commit0}.tar.gz#/%{name}-%{shortcommit0}.tar.gz
 %else
 Source0:    https://github.com/pkuvcl/%{name}/archive/%{version}.tar.gz#/%{name}-%{version}.tar.gz
@@ -44,7 +44,7 @@ This package contains the shared library development files.
 
 %prep
 # Use flat condition or it fails on EPEL 7
-%if "%len %{commit0}" != 0
+%if %{commit0} != %nil
 %autosetup -n %{name}-%{commit0}
 %else
 %autosetup

anda/lib/davs2/update.rhai

@@ -1,5 +1,5 @@
 rpm.version(gh_tag("pkuvcl/davs2"));
 if rpm.changed() {
-    rpm.global("commit0", "");
+    rpm.global("commit0", "%nil");
     rpm.release();
 }