The log message contains user-controlled strings that could include
things like terminal control characters. Space characters in the
command path are now also escaped.
Command line arguments that contain spaces are surrounded with
single quotes and any literal single quote or backslash characters
are escaped with a backslash. This makes it possible to distinguish
multiple command line arguments from a single argument that contains
spaces.
Issue found by Matthieu Barjole and Victor Cutillas of Synacktiv
(https://synacktiv.com).
