Don't treat filename collisions as fatal.

src/av98/client.py

@@ -1270,10 +1270,8 @@ Use 'ls -l' to see URLs."""
         # Derive a filename if one hasn't been set
         if not filename:
             filename = gi.derive_filename(self.mime if saving_current else None)
-
-        # Check for filename collisions
-        if os.path.exists(filename):
-            print("File %s already exists!" % filename)
+        filename = util.handle_filename_collisions(filename)
+        if not filename:
             return
 
         # Actually do the save operation

src/av98/util.py

@@ -1,7 +1,15 @@
+import os.path
+
 # Cheap and cheerful URL detector
 def looks_like_url(word):
     return "." in word and word.startswith("gemini://")
 
+def handle_filename_collisions(filename):
+    while os.path.exists(filename):
+        print("File %s already exists!" % filename)
+        filename = input("Choose a new one, or leave blank to abort: ")
+    return filename
+
 def ask_yes_no(prompt, default=None):
     print(prompt)
     if default == True: