util._hgexecutable: default to 'hg'
This should make hooks work even if util.set_hgexecutable is not called
(e.g. hgweb.cgi).
Fixes issue625.
#!/bin/sh# a test for issue586hg init acd aecho a > ahg ci -Amahg init ../bcd ../becho b > bhg ci -Ambhg pull -f ../ahg mergehg rm -f ahg ci -Amchg st -A