Support accessing remote registries via ssh

The URL has to be given as "ssh://[user@]host.xz[:port]/path/to/repo.git"
rather than the shorter version "[user@]host.xz:path/to/repo.git"

shpc/main/registry/provider.py

@@ -33,7 +33,7 @@ class Provider:
     """
 
     def __init__(self, source, *args, **kwargs):
-        if not (source.startswith("https://") or os.path.exists(source)):
+        if not (source.startswith("https://") or source.startswith("ssh://") or os.path.exists(source)):
             raise ValueError(
                 "Registry source must exist on the filesystem or be given as https://."
             )
@@ -44,7 +44,7 @@ def exists(self, name):
 
     @property
     def is_filesystem_registry(self):
-        return not self.source.startswith("http") and os.path.exists(self.source)
+        return not (self.source.startswith("http") or self.source.startswith("ssh")) and os.path.exists(self.source)
 
     @property
     def name(self):

shpc/main/registry/remote.py

@@ -104,7 +104,7 @@ def __init__(self, *args, **kwargs):
 
     @classmethod
     def matches(cls, source):
-        return cls.provider_name in source and source.startswith("http")
+        return cls.provider_name in source and (source.startswith("http") or source.startswith("ssh"))
 
     @property
     def source_url(self):
@@ -190,6 +190,8 @@ def _update_cache(self, force=False):
         if self._cache and not force:
             return
 
+        if self.source.startswith("ssh"):
+            return self._update_clone_cache()
         # Check for exposed library API on GitHub or GitLab pages
         response = requests.get(self.web_url)
         if response.status_code != 200: