ledger: bump min btchip-python version

and minor simplification

contrib/requirements/requirements-hw.txt

@@ -11,7 +11,7 @@ Cython>=0.27
 trezor[hidapi]>=0.12.0
 safet>=0.1.5
 keepkey>=6.3.1
-btchip-python>=0.1.26
+btchip-python>=0.1.30
 ckcc-protocol>=0.7.7
 bitbox02>=3.0.0
 hidapi

electrum/plugins/ledger/ledger.py

@@ -18,7 +18,7 @@ from electrum.base_wizard import ScriptTypeNotSupported
 from electrum.logging import get_logger
 
 from ..hw_wallet import HW_PluginBase, HardwareClientBase
-from ..hw_wallet.plugin import is_any_tx_output_on_change_branch, validate_op_return_output
+from ..hw_wallet.plugin import is_any_tx_output_on_change_branch, validate_op_return_output, LibraryFoundButUnusable
 
 
 _logger = get_logger(__name__)
@@ -45,7 +45,6 @@ MULTI_OUTPUT_SUPPORT = '1.1.4'
 SEGWIT_SUPPORT = '1.1.10'
 SEGWIT_SUPPORT_SPECIAL = '1.0.4'
 SEGWIT_TRUSTEDINPUTS = '1.4.0'
-UTIL_SEGWIT_TRUSTEDINPUTS = '0.1.29'
 
 
 def test_pin_unlocked(func):
@@ -188,12 +187,7 @@ class Ledger_Client(HardwareClientBase):
             self.multiOutputSupported = versiontuple(firmware) >= versiontuple(MULTI_OUTPUT_SUPPORT)
             self.nativeSegwitSupported = versiontuple(firmware) >= versiontuple(SEGWIT_SUPPORT)
             self.segwitSupported = self.nativeSegwitSupported or (firmwareInfo['specialVersion'] == 0x20 and versiontuple(firmware) >= versiontuple(SEGWIT_SUPPORT_SPECIAL))
-            try:
-                import btchip
-                utilVersion = btchip.__version__
-            except:
-                utilVersion = "0.0.0"                
-            self.segwitTrustedInputs = versiontuple(firmware) >= versiontuple(SEGWIT_TRUSTEDINPUTS) and versiontuple(utilVersion) >= versiontuple(UTIL_SEGWIT_TRUSTEDINPUTS)
+            self.segwitTrustedInputs = versiontuple(firmware) >= versiontuple(SEGWIT_TRUSTEDINPUTS)
 
             if not checkFirmware(firmwareInfo):
                 self.close()
@@ -454,7 +448,7 @@ class Ledger_KeyStore(Hardware_KeyStore):
                     tmp += bfh(int_to_hex(utxo[6], 8))  # txin['value']
                     chipInputs.append({'value' : tmp, 'witness' : True, 'sequence' : sequence})
                     redeemScripts.append(bfh(utxo[2]))
-                elif (not p2shTransaction) or (p2shTransaction and client_electrum.supports_multi_output()):
+                elif (not p2shTransaction) or client_electrum.supports_multi_output():
                     txtmp = bitcoinTransaction(bfh(utxo[0]))
                     trustedInput = self.get_client().getTrustedInput(txtmp, utxo[1])
                     trustedInput['sequence'] = sequence
@@ -573,8 +567,8 @@ class Ledger_KeyStore(Hardware_KeyStore):
             self.handler.finished()
 
 class LedgerPlugin(HW_PluginBase):
-    libraries_available = BTCHIP
     keystore_class = Ledger_KeyStore
+    minimum_library = (0, 1, 30)
     client = None
     DEVICE_IDS = [
                    (0x2581, 0x1807), # HW.1 legacy btchip
@@ -596,9 +590,24 @@ class LedgerPlugin(HW_PluginBase):
     def __init__(self, parent, config, name):
         self.segwit = config.get("segwit")
         HW_PluginBase.__init__(self, parent, config, name)
-        if self.libraries_available:
+        self.libraries_available = self.check_libraries_available()
+        if not self.libraries_available:
+            return
         self.device_manager().register_devices(self.DEVICE_IDS, plugin=self)
 
+    def get_library_version(self):
+        try:
+            import btchip
+            version = btchip.__version__
+        except ImportError:
+            raise
+        except:
+            version = "unknown"
+        if BTCHIP:
+            return version
+        else:
+            raise LibraryFoundButUnusable(library_version=version)
+
     def get_btchip_device(self, device):
         ledger = False
         if device.product_key[0] == 0x2581 and device.product_key[1] == 0x3b7c: