Consider all SSL errors as temporary.

There are a lot of bug reports from people where various SSL errors cause
a crash but are actually just temporary. On the other hand, we have no
information if this ever revealed a problem where retrying was not the right
choice.

Fixes issue s3ql#87.
Fixes issue s3ql#252.

Changes.txt

@@ -15,6 +15,9 @@ UNRELEASED CHANGES
     mounted again on the same system without having been mounted
     elsewhere.
 
+  * S3QL now considers all SSL-related errors as temporary and
+    automatically retries (instead of bailing out).
+
 2018-10-08, S3QL 2.31
 
   * Object removal now makes more use of parallelism.

src/s3ql/backends/s3c.py

@@ -170,12 +170,12 @@ def is_temp_failure(self, exc): #IGNORE:W0613
                or exc.status == 408)):
             return True
 
-        # Temporary workaround for
-        # https://bitbucket.org/nikratio/s3ql/issues/87 and
-        # https://bitbucket.org/nikratio/s3ql/issues/252
-        elif (isinstance(exc, ssl.SSLError) and
-              (str(exc).startswith('[SSL: BAD_WRITE_RETRY]') or
-               str(exc).startswith('[SSL: BAD_LENGTH]'))):
+        # Consider all SSL errors as temporary. There are a lot of bug
+        # reports from people where various SSL errors cause a crash
+        # but are actually just temporary. On the other hand, we have
+        # no information if this ever revealed a problem where retrying
+        # was not the right choice.
+        elif isinstance(exc, ssl.SSLError):
             return True
 
         return False