test-grep: use lowercase hg command

tests/test-grep

@@ -1,68 +1,68
 #!/bin/sh
 
 mkdir t
 cd t
 hg init
 echo import > port
 hg add port
 hg commit -m 0 -u spam -d '0 0'
 echo export >> port
 hg commit -m 1 -u eggs -d '1 0'
 echo export > port
 echo vaportight >> port
 echo 'import/export' >> port
 hg commit -m 2 -u spam -d '2 0'
 echo 'import/export' >> port
 hg commit -m 3 -u eggs -d '3 0'
 head -n 3 port > port1
 mv port1 port
 hg commit -m 4 -u spam -d '4 0'
 echo % pattern error
 hg grep '**test**'
 echo % simple
 hg grep port port
 echo % all
 hg grep --all -nu port port
 echo % other
 hg grep import port
 
 hg cp port port2
 hg commit -m 4 -u spam -d '5 0'
 echo '% follow'
 hg grep -f 'import$' port2
 echo deport >> port2
 hg commit -m 5 -u eggs -d '6 0'
 hg grep -f --all -nu port port2
 
 cd ..
 hg init t2
 cd t2
 hg grep foobar foo
 hg grep foobar
 echo blue >> color
 echo black >> color
 hg add color
 hg ci -m 0 -d '0 0'
 echo orange >> color
 hg ci -m 1 -d '0 0'
 echo black > color
 hg ci -m 2 -d '0 0'
 echo orange >> color
 echo blue >> color
 hg ci -m 3 -d '0 0'
 hg grep orange
 hg grep --all orange
 
 # Got a traceback when using grep on a single
 # revision with renamed files.
 cd ..
 echo % issue 685
 hg init issue685
 cd issue685
 echo octarine > color
 hg ci -Amcolor
 hg rename color colour
-Hg ci -Am rename
+hg ci -Am rename
 hg grep octarine
 # Used to crash here
 hg grep -r 1 octarine