Postgres server version reported incorrectly for psql >= 10

[Ryan J Ollos]

The About Trac page on my dev machine is showing server: 10.0.4. It should display 10.4:

$ psql -c "SELECT version();" trac tracuser
                                                    version
---------------------------------------------------------------------------------------------------------------
 PostgreSQL 10.4 on x86_64-apple-darwin17.5.0, compiled by Apple LLVM version 9.1.0 (clang-902.0.39.1), 64-bit
(1 row)

I've done only a cursory investigation, but it looks like the ​versioning policy has changed. So for version ≥ 10 we should parse 100004 to tuple (10, 4): tags/trac-1.3.2/trac/db/postgres_backend.py@:454:#L452​.

trac/db/postgres_backend.py

@@ -99 +99 @@
 def _version_tuple(ver):
 
     if ver:
-        # Extract 9.1.23 from 90123.
         def get_digit(version, n):
             return version / 10 ** (2 * n) % 100
-        return get_digit(ver, 2), get_digit(ver, 1), get_digit(ver, 0)
+        first_digit = get_digit(ver, 2)
+        if first_digit >= 10:
+            # Extract (10, 4) from 100004.
+            return first_digit, get_digit(ver, 0)
+        else:
+            # Extract (9, 1, 23) from 90123.
+            return first_digit, get_digit(ver, 1), get_digit(ver, 0)
 
 
 def _version_string(ver):

A few other minor changes may also be needed.