The current Varnish-Cache version in distributions
repositories is currently 7.7.x causing the
following errors on build:
```
In file included from /usr/include/varnish/cache/cache.h:51,
                 from ../../../src/vmod_blobdigest.c:33:
../../../src/vmod_blobdigest.c: In function 'ws_alloc_digest':
/usr/include/varnish/miniobj.h:17:21: error: 'struct vrt_blob' has no member named 'magic'
   17 |                 (to)->magic = (type_magic);                             \
      |                     ^~
../../../src/vmod_blobdigest.c:379:9: note: in expansion of macro 'INIT_OBJ'
  379 |         INIT_OBJ(b, VRT_BLOB_MAGIC);
      |         ^~~~~~~~
../../../src/vmod_blobdigest.c:379:21: error: 'VRT_BLOB_MAGIC' undeclared (first use in this function); did you mean 'VRT_CTX_MAGIC'?
  379 |         INIT_OBJ(b, VRT_BLOB_MAGIC);
      |                     ^~~~~~~~~~~~~~
/usr/include/varnish/miniobj.h:17:32: note: in definition of macro 'INIT_OBJ'
   17 |                 (to)->magic = (type_magic);                             \
      |                                ^~~~~~~~~~
../../../src/vmod_blobdigest.c:379:21: note: each undeclared identifier is reported only once for each function it appears in
  379 |         INIT_OBJ(b, VRT_BLOB_MAGIC);
      |                     ^~~~~~~~~~~~~~
/usr/include/varnish/miniobj.h:17:32: note: in definition of macro 'INIT_OBJ'
   17 |                 (to)->magic = (type_magic);                             \
      |                                ^~~~~~~~~~
../../../src/vmod_blobdigest.c: In function 'heap_alloc_digest':
/usr/include/varnish/miniobj.h:17:21: error: 'struct vrt_blob' has no member named 'magic'
   17 |                 (to)->magic = (type_magic);                             \
      |                     ^~
../../../src/vmod_blobdigest.c:404:9: note: in expansion of macro 'INIT_OBJ'
  404 |         INIT_OBJ(b, VRT_BLOB_MAGIC);
      |         ^~~~~~~~
../../../src/vmod_blobdigest.c:404:21: error: 'VRT_BLOB_MAGIC' undeclared (first use in this function); did you mean 'VRT_CTX_MAGIC'?
  404 |         INIT_OBJ(b, VRT_BLOB_MAGIC);
      |                     ^~~~~~~~~~~~~~
/usr/include/varnish/miniobj.h:17:32: note: in definition of macro 'INIT_OBJ'
   17 |                 (to)->magic = (type_magic);                             \
      |                                ^~~~~~~~~~
```
Cloning Varnish-Cache in the pipeline allows
getting the latest version and prevent the error.