Fixes #1557890.

Backported from trunk.

section with a link to the tutorial sections.

Backported from trunk.

 (backport from rev. 52497)

Point users to the subprocess module in the docs for os.system, os.spawn*, os.popen2, and the popen2 and commands modules

 (backport from rev. 52311)

about the case of filenames.
 (backport from rev. 52309)

(bug #1556261).
 (backport from rev. 52307)

 (backport from rev. 52303)

 (backport from rev. 52297)

 (backport from rev. 52293)

- remove Sleepycat name now that they have been bought

string pointed to by its parameter.
 (backport from rev. 52078)

 (backport from rev. 52063)

 (backport from rev. 52053)

Since this paragraph is about exception's message attribute(2.5 feature),
I will not backport to 2.4 branch.

(damn, it's nice to see the line
  #define PY_VERSION              "2.5"
in patchlevel.h)

and to include the default value

- minor markup cleanup

 (backport)

to use "in".
 (backport from rev. 51740)

Partially from SF patch #1551339, but also taken from head.