Add support for building from git snapshots for packit

python-drgn.spec

@@ -41,6 +41,10 @@ BuildRequires:  elfutils-devel
 BuildRequires:  libkdumpfile-devel
 BuildRequires:  zlib-devel
 BuildRequires:  xz-devel
+# These are needed when building from git snapshots
+BuildRequires:  autoconf
+BuildRequires:  automake
+BuildRequires:  libtool
 
 %description %{_description}
 
@@ -70,6 +74,10 @@ sed -r \
     -e 's|https://docs.python.org/3|%{_docdir}/python3-docs/html|' \
     -i docs/conf.py
 %endif
+# Ensure version is always set, even when building from git snapshots
+if [ ! -f drgn/internal/version.py ]; then
+  echo '__version__ = "%{version}"' > drgn/internal/version.py
+fi
 
 %build
 # verbose build