Sometime ago I was in python mode and incorrectly indented a line of the
shell script with spaces instead of tabs. Shame on me. This should bring
things back to their natural order.
In situations where 2.7 is available and some unsupported 3.x is the
system's default we should probably fallback to 2.7 instead of the
default (that might be e.g. 3.4). This might fix#78.