merge: make test for fast-forward merge stricter (issue619)
don't allow merging with an ancestor
fix != on contexts
add a test
#!/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