Add options to enable installation of pre-release packages

Signed-off-by: Matthew Ballance <matt.ballance@gmail.com>

Author: mballance

src/ivpm/__main__.py

@@ -215,6 +215,9 @@ def get_parser():
     update_cmd.add_argument("-a", "--anonymous-git", dest="anonymous", 
         action="store_true",
         help="Clones git repositories in 'anonymous' mode")
+    update_cmd.add_argument("--py-prerls-packages", dest="anonymous", 
+        action="store_true",
+        help="Installs pre-release Python packages")
 #    update_cmd.add_argument("-r", "--requirements", dest="requirements")
 
     init_cmd = subparser.add_parser("init",

src/ivpm/cmds/cmd_update.py

@@ -279,6 +279,9 @@ def __call__(self, args):
                     "install",
                     "-r",
                     reqfile]
+                
+                if args.py_prerls_packages:
+                    cmd.append("--pre")
 
                 status = subprocess.run(cmd, env=env)