ipalib: Handle percent signs in saved values

Turn off string interpolation on the FileStore class to avoid
exceptions when a value to be saved contains a percent sign (%).
The underlying SafeConfigParser that is used interprets percent
signs as placeholders to be interpolated which then causes an
exception as the placeholder isn't properly formatted.

ipa-client-install uses the FileStore class to backup certain
values that it overwrites as part of the installation. If those
pre-existing, backed-up values contained a percent sign,
ipa-client-install would throw an exception and thus prevent
installation.

https://pagure.io/freeipa/issue/9085

Reviewed-By: Rob Crittenden <rcritten@redhat.com>

ipalib/sysrestore.py

@@ -82,7 +82,7 @@ class FileStore:
 
         self.files = {}
 
-        p = SafeConfigParser()
+        p = SafeConfigParser(interpolation=None)
         p.optionxform = str
         p.read(self._index)
 
@@ -103,7 +103,7 @@ class FileStore:
                 os.remove(self._index)
             return
 
-        p = SafeConfigParser()
+        p = SafeConfigParser(interpolation=None)
         p.optionxform = str
 
         p.add_section('files')
@@ -344,7 +344,7 @@ class StateFile:
 
         self.modules = {}
 
-        p = SafeConfigParser()
+        p = SafeConfigParser(interpolation=None)
         p.optionxform = str
         p.read(self._path)
 
@@ -373,7 +373,7 @@ class StateFile:
                 os.remove(self._path)
             return
 
-        p = SafeConfigParser()
+        p = SafeConfigParser(interpolation=None)
         p.optionxform = str
 
         for module in self.modules: