test-merge-prompt.t: unset HGMERGE

We're going to test behavior with and without HGMERGE, so disable it for the
test.

tests/test-merge-prompt.t

@@ -1,172 +1,175 b''
 Test for
 b5605d88dc27: Make ui.prompt repeat on "unrecognized response" again
  (issue897)
 
 840e2b315c1f: Fix misleading error and prompts during update/merge
  (issue556)
 
+Make sure HGMERGE doesn't interfere with the test
+  $ unset HGMERGE
+
   $ status() {
   >     echo "--- status ---"
   >     hg st -A file1 file2
   >     for file in file1 file2; do
   >         if [ -f $file ]; then
   >             echo "--- $file ---"
   >             cat $file
   >         else
   >             echo "*** $file does not exist"
   >         fi
   >     done
   > }
 
   $ hg init
 
   $ echo 1 > file1
   $ echo 2 > file2
   $ hg ci -Am 'added file1 and file2'
   adding file1
   adding file2
 
   $ hg rm file1
   $ echo changed >> file2
   $ hg ci -m 'removed file1, changed file2'
 
   $ hg co 0
   2 files updated, 0 files merged, 0 files removed, 0 files unresolved
 
   $ echo changed >> file1
   $ hg rm file2
   $ hg ci -m 'changed file1, removed file2'
   created new head
 
 
 Non-interactive merge:
 
   $ hg merge -y
   local changed file1 which remote deleted
   use (c)hanged version or (d)elete? c
   remote changed file2 which local deleted
   use (c)hanged version or leave (d)eleted? c
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
 
   $ status
   --- status ---
   M file2
   C file1
   --- file1 ---
   1
   changed
   --- file2 ---
   2
   changed
 
 
 Interactive merge:
 
   $ hg co -C
   0 files updated, 0 files merged, 1 files removed, 0 files unresolved
 
   $ hg merge --config ui.interactive=true <<EOF
   > c
   > d
   > EOF
   local changed file1 which remote deleted
   use (c)hanged version or (d)elete? c
   remote changed file2 which local deleted
   use (c)hanged version or leave (d)eleted? d
   0 files updated, 0 files merged, 0 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
 
   $ status
   --- status ---
   file2: * (glob)
   C file1
   --- file1 ---
   1
   changed
   *** file2 does not exist
 
 
 Interactive merge with bad input:
 
   $ hg co -C
   0 files updated, 0 files merged, 0 files removed, 0 files unresolved
 
   $ hg merge --config ui.interactive=true <<EOF
   > foo
   > bar
   > d
   > baz
   > c
   > EOF
   local changed file1 which remote deleted
   use (c)hanged version or (d)elete? foo
   unrecognized response
   local changed file1 which remote deleted
   use (c)hanged version or (d)elete? bar
   unrecognized response
   local changed file1 which remote deleted
   use (c)hanged version or (d)elete? d
   remote changed file2 which local deleted
   use (c)hanged version or leave (d)eleted? baz
   unrecognized response
   remote changed file2 which local deleted
   use (c)hanged version or leave (d)eleted? c
   1 files updated, 0 files merged, 1 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
 
   $ status
   --- status ---
   M file2
   R file1
   *** file1 does not exist
   --- file2 ---
   2
   changed
 
 
 Interactive merge with not enough input:
 
   $ hg co -C
   1 files updated, 0 files merged, 1 files removed, 0 files unresolved
 
   $ hg merge --config ui.interactive=true <<EOF
   > d
   > EOF
   local changed file1 which remote deleted
   use (c)hanged version or (d)elete? d
   remote changed file2 which local deleted
   use (c)hanged version or leave (d)eleted? abort: response expected
   [255]
 
   $ status
   --- status ---
   file2: * (glob)
   C file1
   --- file1 ---
   1
   changed
   *** file2 does not exist
 
 Non-interactive linear update
 
   $ hg co -C 0
   2 files updated, 0 files merged, 0 files removed, 0 files unresolved
   $ echo changed >> file1
   $ hg rm file2
   $ hg update 1 -y
   local changed file1 which remote deleted
   use (c)hanged version or (d)elete? c
   remote changed file2 which local deleted
   use (c)hanged version or leave (d)eleted? c
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
   $ status
   --- status ---
   A file1
   C file2
   --- file1 ---
   1
   changed
   --- file2 ---
   2
   changed