fix for --solv regression

mythril/ethereum/util.py

@@ -79,7 +79,7 @@ def solc_exists(version):
             ".py-solc/solc-v" + version,
             "bin/solc",
         ),  # py-solc setup
-        "/usr/bin/solc",  # Ubuntu PPA setup
+        #"/usr/bin/solc",  # Ubuntu PPA setup
     ]
     for solc_path in solc_binaries:
         if os.path.exists(solc_path):

mythril/mythril.py

@@ -227,6 +227,9 @@ class Mythril(object):
             else:
                 try:
                     solc.install_solc("v" + version)
+                    solc_binary = util.solc_exists(version)
+                    if not solc_binary:
+                        raise SolcError()
                 except SolcError:
                     raise CriticalError(
                         "There was an error when trying to install the specified solc version"