move wallet upgrade docs and improve wallet opening error handling

docs/release-notes/release-notes-future.md

@@ -1,29 +0,0 @@
-Joinmarket-clientserver future:
-===============================
-
-
-Upgrading 
-=========
-
-To upgrade: run the `install.sh` script as mentioned in the README. When prompted to overwrite the directory `jmvenv`, accept.
-
-A new wallet format has been introduced. Old wallets require conversion. In order to convert your existing wallet to the new format you can use the included conversion tool at `scripts/convert_old_wallet.py`.
-
-usage:
-
-    python convert_old_wallet.py full/path/to/wallets/wallet.json
-
-This will place the newly converted `wallet.jmdat` file in the existing joinmarket `wallets/` directory. The wallet name will be adopted accordingly if it differs from `wallet`.
-
-
-Notable changes
-===============
-
-
-Credits
-=======
-
-Thanks to everyone who directly contributed to this release -
-
-
-And thanks also to those who submitted bug reports, tested and otherwise helped out.

docs/wallet-upgrade.md

@@ -0,0 +1,14 @@
+A new wallet format has been introduced. Old wallets require conversion.
+In order to convert your existing wallet to the new format you can use the
+included conversion tool at `scripts/convert_old_wallet.py`.
+
+usage:
+
+    python convert_old_wallet.py full/path/to/wallets/wallet.json
+
+This will place the newly converted `wallet.jmdat` file in the existing
+joinmarket `wallets/` directory. The wallet name will be adopted accordingly
+if it differs from `wallet`.
+
+There is no need to move funds to the new wallet. All your funds, addresses,
+private keys, history and also your seed will be retained.

jmclient/jmclient/wallet_utils.py

@@ -907,7 +907,16 @@ def open_wallet(path, ask_for_password=True, password=None, read_only=False,
     returns:
         wallet object
     """
-    if ask_for_password:
+    if not os.path.isfile(path):
+        raise Exception("Failed to open wallet at '{}': not a file".format(path))
+
+    if not Storage.is_storage_file(path):
+        raise Exception("Failed to open wallet at '{}': not a valid joinmarket"
+                        " wallet.\n\nIf this wallet is in the old json format "
+                        "you need to convert it using the conversion script"
+                        "at `scripts/convert_old_wallet.py`".format(path))
+
+    if ask_for_password and Storage.is_encrypted_storage_file(path):
         while True:
             try:
                 # do not try empty password, assume unencrypted on empty password